Randomized tests in CppunitTest_basegfx

[Stephan Bergmann]

<https://ci.libreoffice.org//job/lo_ubsan/2691> failed 
CppunitTest_basegfx with

> /basegfx/source/polygon/b2dtrapezoid.cxx:179:68: runtime error: division by zero
>     #0 0x7fe03ea50e6c in basegfx::trapezoidhelper::(anonymous namespace)::TrDeEdgeEntry::getCutPointForGivenY(double) const /basegfx/source/polygon/b2dtrapezoid.cxx:179:68
>     #1 0x7fe03ea43ad9 in basegfx::trapezoidhelper::(anonymous namespace)::TrapezoidSubdivider::Subdivide(std::__debug::vector<basegfx::B2DTrapezoid, std::allocator<basegfx::B2DTrapezoid> >&) /basegfx/source/polygon/b2dtrapezoid.cxx:668:46
>     #2 0x7fe03ea40bfc in basegfx::utils::trapezoidSubdivide(std::__debug::vector<basegfx::B2DTrapezoid, std::allocator<basegfx::B2DTrapezoid> >&, basegfx::B2DPolyPolygon const&) /basegfx/source/polygon/b2dtrapezoid.cxx:940:34
>     #3 0x7fe03f5a5f29 in basegfx::b2dpolypolygon::testTrapezoidHelper() /basegfx/test/B2DPolyPolygonTest.cxx:64:9
>     #4 0x7fe03f5ab267 in void std::__invoke_impl<void, void (basegfx::b2dpolypolygon::*&)(), basegfx::b2dpolypolygon*&>(std::__invoke_memfun_deref, void (basegfx::b2dpolypolygon::*&)(), basegfx::b2dpolypolygon*&) /opt/rh/devtoolset-7/root/usr/lib/gcc/x86_64-redhat-linux/7/../../../../include/c++/7/bits/invoke.h:73:14
>     #5 0x7fe03f5aaed4 in std::__invoke_result<void (basegfx::b2dpolypolygon::*&)(), basegfx::b2dpolypolygon*&>::type std::__invoke<void (basegfx::b2dpolypolygon::*&)(), basegfx::b2dpolypolygon*&>(void (basegfx::b2dpolypolygon::*&)(), basegfx::b2dpolypolygon*&) /opt/rh/devtoolset-7/root/usr/lib/gcc/x86_64-redhat-linux/7/../../../../include/c++/7/bits/invoke.h:95:14
>     #6 0x7fe03f5aad50 in void std::_Bind<void (basegfx::b2dpolypolygon::* (basegfx::b2dpolypolygon*))()>::__call<void, 0ul>(std::tuple<>&&, std::_Index_tuple<0ul>) /opt/rh/devtoolset-7/root/usr/lib/gcc/x86_64-redhat-linux/7/../../../../include/c++/7/functional:467:11
>     #7 0x7fe03f5aaa24 in void std::_Bind<void (basegfx::b2dpolypolygon::* (basegfx::b2dpolypolygon*))()>::operator()<void>() /opt/rh/devtoolset-7/root/usr/lib/gcc/x86_64-redhat-linux/7/../../../../include/c++/7/functional:549:17
>     #8 0x7fe03f5a9c3c in std::_Function_handler<void (), std::_Bind<void (basegfx::b2dpolypolygon::* (basegfx::b2dpolypolygon*))()> >::_M_invoke(std::_Any_data const&) /opt/rh/devtoolset-7/root/usr/lib/gcc/x86_64-redhat-linux/7/../../../../include/c++/7/bits/std_function.h:316:2
>     #9 0x7fe03f532561 in std::function<void ()>::operator()() const /opt/rh/devtoolset-7/root/usr/lib/gcc/x86_64-redhat-linux/7/../../../../include/c++/7/bits/std_function.h:706:14
>     #10 0x7fe03f5a9028 in CppUnit::TestCaller<basegfx::b2dpolypolygon>::runTest() /workdir/UnpackedTarball/cppunit/include/cppunit/TestCaller.h:175:7
>     #11 0x7fe04bb5de8b in CppUnit::TestCaseMethodFunctor::operator()() const (/workdir/UnpackedTarball/cppunit/src/cppunit/.libs/libcppunit-1.15.so.1+0x296e8b)
>     #12 0x7fe04bacf172 in CppUnit::DefaultProtector::protect(CppUnit::Functor const&, CppUnit::ProtectorContext const&) (/workdir/UnpackedTarball/cppunit/src/cppunit/.libs/libcppunit-1.15.so.1+0x208172)
>     #13 0x7fe04bb3266c in CppUnit::ProtectorChain::ProtectFunctor::operator()() const (/workdir/UnpackedTarball/cppunit/src/cppunit/.libs/libcppunit-1.15.so.1+0x26b66c)
>     #14 0x7fe04bb2c958 in CppUnit::ProtectorChain::protect(CppUnit::Functor const&, CppUnit::ProtectorContext const&) (/workdir/UnpackedTarball/cppunit/src/cppunit/.libs/libcppunit-1.15.so.1+0x265958)
>     #15 0x7fe04bbc166d in CppUnit::TestResult::protect(CppUnit::Functor const&, CppUnit::Test*, std::string const&) (/workdir/UnpackedTarball/cppunit/src/cppunit/.libs/libcppunit-1.15.so.1+0x2fa66d)
>     #16 0x7fe04bb5c2a7 in CppUnit::TestCase::run(CppUnit::TestResult*) (/workdir/UnpackedTarball/cppunit/src/cppunit/.libs/libcppunit-1.15.so.1+0x2952a7)
>     #17 0x7fe04bb60411 in CppUnit::TestComposite::doRunChildTests(CppUnit::TestResult*) (/workdir/UnpackedTarball/cppunit/src/cppunit/.libs/libcppunit-1.15.so.1+0x299411)
>     #18 0x7fe04bb5f668 in CppUnit::TestComposite::run(CppUnit::TestResult*) (/workdir/UnpackedTarball/cppunit/src/cppunit/.libs/libcppunit-1.15.so.1+0x298668)
>     #19 0x7fe04bb60411 in CppUnit::TestComposite::doRunChildTests(CppUnit::TestResult*) (/workdir/UnpackedTarball/cppunit/src/cppunit/.libs/libcppunit-1.15.so.1+0x299411)
>     #20 0x7fe04bb5f668 in CppUnit::TestComposite::run(CppUnit::TestResult*) (/workdir/UnpackedTarball/cppunit/src/cppunit/.libs/libcppunit-1.15.so.1+0x298668)
>     #21 0x7fe04bbeb936 in CppUnit::TestRunner::WrappingSuite::run(CppUnit::TestResult*) (/workdir/UnpackedTarball/cppunit/src/cppunit/.libs/libcppunit-1.15.so.1+0x324936)
>     #22 0x7fe04bbc012e in CppUnit::TestResult::runTest(CppUnit::Test*) (/workdir/UnpackedTarball/cppunit/src/cppunit/.libs/libcppunit-1.15.so.1+0x2f912e)
>     #23 0x7fe04bbec7f2 in CppUnit::TestRunner::run(CppUnit::TestResult&, std::string const&) (/workdir/UnpackedTarball/cppunit/src/cppunit/.libs/libcppunit-1.15.so.1+0x3257f2)
>     #24 0x5062ee in (anonymous namespace)::ProtectedFixtureFunctor::run() const /sal/cppunittester/cppunittester.cxx:333:20
>     #25 0x502ce7 in main2() /sal/cppunittester/cppunittester.cxx:483:16
>     #26 0x50114e in sal_main() /sal/cppunittester/cppunittester.cxx:622:14
>     #27 0x500f9e in main /sal/cppunittester/cppunittester.cxx:617:1
>     #28 0x7fe049c4c554 in __libc_start_main /usr/src/debug/glibc-2.17-c758a686/csu/../csu/libc-start.c:266
>     #29 0x425854 in _start (/workdir/LinkTarget/Executable/cppunittester+0x425854)

in testTrapezoidHelper that had originally been introduced in 
<https://git.libreoffice.org/core/+/82b56544a7a53528970632d086c3cfd8ef879335%5E!/> 
"basegfx: accelerate Trapezoid subdivision by avoiding allocations" and 
apparently uses random data (via basegfx2d::getRandomOrdinal, defined in 
basegfx/test/boxclipper.cxx), so that runs of CppunitTest_basegfx are 
not reproducible (so that there's no good way to reproduce and fix the 
above division by zero error).  Can that test be made reproducible please?