nvptx 'TARGET_USE_LOCAL_THUNK_ALIAS_P', 'TARGET_SUPPORTS_ALIASES'
This fixes up commit
f8b15e177155960017ac0c5daef8780d1127f91c
"[nvptx] Use .alias directive for mptx >= 6.3", which regressed in
particular C++ test cases if the new '-malias' flag was not active.
In that case, we have to maintain (that is now, restore) the previous
state of 'TARGET_USE_LOCAL_THUNK_ALIAS_P', 'TARGET_SUPPORTS_ALIASES'.
The remaining three regressions are to be resolved via
<https://inbox.sourceware.org/87ledgzxcl.fsf@euler.schwinge.homeip.net>
"More '#ifdef ASM_OUTPUT_DEF' -> 'if (TARGET_SUPPORTS_ALIASES)' etc.".
gcc/
* config/nvptx/nvptx.h (TARGET_USE_LOCAL_THUNK_ALIAS_P)
(TARGET_SUPPORTS_ALIASES): Define.