Restore bootstrap on ARM
The -Wuse-after-free warning is explicitly disabled for destructors on ARM
because of the special ABI and the previous change to the warning machinery
uncovered another case where the warning data would be incorrectly erased.
gcc/
* warning-control.cc (copy_warning) [generic version]: Do not erase
the warning data of the destination location when the no-warning
bit is not set on the source.
(copy_warning) [tree version]: Return early if TO is equal to FROM.
(copy_warning) [gimple version]: Likewise.
gcc/testsuite/
* g++.dg/warn/Wuse-after-free5.C: New test.