LTO: Prune some warnings in the testsuite
Warnings like:
warning: using serial compilation of 2 LTRANS jobs
warning: visibility attribute not supported in this configuration; ignored\[^\n\]*" $text "" text
are pruned by lto.exp, but not for LTO testcases when run in other parts
of the testsuite. They will be, now.
gcc/testsuite/ChangeLog:
PR testsuite/47334
PR testsuite/103823
* lib/prune.exp: Prune some warnings related to LTO and
visibility.
(cherry picked from commit
05edf6c470ae0ab50d42f16e78e476dbcc774842)