[Bug libgcc/89714] allow for overriding the thread-detection mechanism

[tneumann at users dot sourceforge.net]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89714

--- Comment #3 from Thomas Neumann <tneumann at users dot sourceforge.net> ---
Perhaps the header files could be changed to react to _REENTRANT, as that seems
to be the define that is set by gcc when requesting threading support.

The redundant checks within the shared library are less of an issue. Of course
they waste a few cycles, too, but the unnecessary checks in the header files
are far worse as they are inlined all over the place when using, e.g.,
shared_ptr.