[Bug sanitizer/57316] [4.8/4.9 regression] build failure in libsanitizer

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57316

--- Comment #14 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
I wouldn't call the conditional SYSCALL_SUPPORTED, but SANITIZER_SUPPORTED or
so.
In the future, the configure could have various other reasons why it should
give up on building any sanitizer libraries altogether.  Also, supposedly
__NR_gettid could be added to the test too.