JunitTest_ucb_complex test hangs after 739aaf02db335 on Linux x86

[Luke Benes]

After https://cgit.freedesktop.org/libreoffice/core/commit/?id=739aaf02db33
    osl::Mutex->std::mutex in bridges/except

On both Arch Linux 32 and OpenSUSE Tumbleweed i686, 'make check' now hangs on JunitTest_ucb_complex. I can consistently reproduce this failure with both clang 13 and gcc 11.  Below is the log. 

Noel, 
Any idea why this might cause a deadlock or infinite loop? What further debugging or system info do you need?   

-Luke


[JUT] ucb_complex
JUnit version 4.13
setUpConnection()
.ftp://noname:nopasswd@*nohost.invalid
now executing open
to rerun just this failed test without all others, run:

    make JunitTest_ucb_complex

cd into the module dir to run the tests faster
Or to do interactive debugging, run two shells with:

    make debugrun
    make gb_JunitTest_DEBUGRUN=T JunitTest_ucb_complex

make[1]: *** [/core/solenv/gbuild/JunitTest.mk:40: /core/workdir/JunitTest/ucb_complex/done] Error 1
make[1]: *** Deleting intermediate file '/core/workdir/CustomTarget/i18npool/breakiterator/dict_word_prepostdash.brk'
make[1]: *** Deleting intermediate file '/core/workdir/CustomTarget/i18npool/breakiterator/edit_word.txt'
make[1]: *** Deleting intermediate file '/core/workdir/CustomTarget/i18npool/breakiterator/line.brk'
make[1]: *** Deleting intermediate file '/core/workdir/CustomTarget/i18npool/breakiterator/sent.brk'
make[1]: *** Deleting intermediate file '/core/workdir/CustomTarget/i18npool/breakiterator/edit_word_hu.txt'
make[1]: *** Deleting intermediate file '/core/workdir/CustomTarget/i18npool/breakiterator/dict_word_hu.brk'
make[1]: *** Deleting intermediate file '/core/workdir/CustomTarget/i18npool/breakiterator/dict_word_he.txt'
make[1]: *** Deleting intermediate file '/core/workdir/CustomTarget/i18npool/breakiterator/edit_word_he.brk'
make[1]: *** Deleting intermediate file '/core/workdir/CustomTarget/i18npool/breakiterator/dict_word.brk'
make[1]: *** Deleting intermediate file '/core/workdir/CustomTarget/i18npool/breakiterator/count_word.brk'
make[1]: *** Deleting intermediate file '/core/workdir/CustomTarget/i18npool/breakiterator/dict_word_hu.txt'
make[1]: *** Deleting intermediate file '/core/workdir/CustomTarget/i18npool/breakiterator/dict_word_nodash.brk'
make[1]: *** Deleting intermediate file '/core/workdir/CustomTarget/i18npool/breakiterator/dict_word.txt'
make[1]: *** Deleting intermediate file '/core/workdir/CustomTarget/i18npool/breakiterator/count_word.txt'
make[1]: *** Deleting intermediate file '/core/workdir/CustomTarget/i18npool/breakiterator/dict_word_prepostdash.txt'
make[1]: *** Deleting intermediate file '/core/workdir/CustomTarget/i18npool/breakiterator/dict_word_he.brk'
make[1]: *** Deleting intermediate file '/core/workdir/CustomTarget/i18npool/breakiterator/line.txt'
make[1]: *** Deleting intermediate file '/core/workdir/CustomTarget/i18npool/breakiterator/edit_word.brk'
make[1]: *** Deleting intermediate file '/core/workdir/CustomTarget/i18npool/breakiterator/edit_word_hu.brk'
make[1]: *** Deleting intermediate file '/core/workdir/CustomTarget/i18npool/breakiterator/dict_word_nodash.txt'
make[1]: *** Deleting intermediate file '/core/workdir/CustomTarget/i18npool/breakiterator/sent.txt'
make[1]: *** Deleting intermediate file '/core/workdir/CustomTarget/i18npool/breakiterator/edit_word_he.txt'
make: *** [Makefile:169: JunitTest_ucb_complex] Interrupt

> uname -a
Linux linux-645r 5.13.4-1-pae #1 SMP Thu Jul 22 15:55:06 UTC 2021 (91a0cca) i686 i686 i386 GNU/Linux
> lsb_release -a
Description:	openSUSE Tumbleweed
Release:	20210726
> clang --version
clang version 13.0.0 (https://github.com/llvm/llvm-project.git eacbd7d25ae08465bcef4fb6d3b86c7dddb2d64f)
Target: i686-pc-linux-gnu