[libcxxabi] Stub out 'sleep' call when _LIBCXXABI_HAS_NO_THREADS is defined.

[abidh]

Summary

While running this test on a bare metal target, I got an error as 'sleep' was not available on that system. As 'sleep' call is not doing anything useful for cases when _LIBCXXABI_HAS_NO_THREADS is defined. This patch puts it under this check.

[ldionne]

This sounds reasonable to me. Do you have commit access? If not, please specify Author Name <email@domain> I should use to commit on your behalf.

[ldionne]

In D89871#2344258, @ldionne wrote:

[...] Do you have commit access? If not, please specify Author Name <email@domain> I should use to commit on your behalf.

I see you do, feel free to go ahead and commit this. Thanks!

libcxxabi/test/test_exception_storage.pass.cpp

void *thread_code (void *parm) {
     if ( NULL == glob1 )
         std::printf("Got null result from __cxa_get_globals\n");
 
     glob2 = __cxxabiv1::__cxa_get_globals_fast ();
     if ( glob1 != glob2 )
         std::printf("Got different globals!\n");
 
     *result = (size_t) glob1;
+#ifndef _LIBCXXABI_HAS_NO_THREADS
     sleep ( 1 );
+#endif
     return parm;
 }
 
 #ifndef _LIBCXXABI_HAS_NO_THREADS
 #define NUMTHREADS  10
 size_t                 thread_globals [ NUMTHREADS ] = { 0 };
 std::__libcpp_thread_t   threads        [ NUMTHREADS ];
 #endif