[cairo] [PATCH v2 3/3] configure.ac: Fix broken build for Qt backend

[Bryce W. Harrington]

When --enable-qt is specified, the build will break due to missing
libstdc++:

  CCLD     cairo-test-suite
/usr/bin/ld: ../boilerplate/.libs/libcairoboilerplate.a(libcairoboilerplate_cxx_la-cairo-boilerplate-qt.o): undefined reference to symbol '__gxx_personality_v0@@CXXABI_1.3'
//usr/lib/x86_64-linux-gnu/libstdc++.so.6: error adding symbols: DSO missing from command line
collect2: error: ld returned 1 exit status

When using g++ to compile and link code, g++ automatically links
libstdc++.  However, in cairo we're using g++ only to compile, so need
to explicitly link against libstdc++ for backends that need iostream,
stl, or other stdc++ features.

Fixes: https://bugs.freedesktop.org/show_bug.cgi?id=59038
Signed-off-by: Bryce Harrington <b.harrington at samsung.com>
---
 configure.ac | 1 +
 1 file changed, 1 insertion(+)

diff --git a/configure.ac b/configure.ac
index 9f38d30..02106f3 100644
--- a/configure.ac
+++ b/configure.ac
@@ -191,6 +191,7 @@ CAIRO_ENABLE_SURFACE_BACKEND(qt, Qt, no, [
 		    [qt_REQUIRES=""
 		     use_qt="no (requires Qt4 development libraries)"
 		     ])
+  qt_NONPKGCONFIG_LIBS="-lstdc++"
 ])
 
 dnl ===========================================================================
-- 
1.9.1