[OpenMP] libomp: Fix possible NULL dereference.

According to dlsym description, the value of symbol could be NULL,
and there is no error in this case. Thus dlerror will also return NULL in
this case. We need to check the value returned by dlerror before printing it.

Differential Revision: https://reviews.llvm.org/D112174

GitOrigin-RevId: c704b25b449418217f2e3ee41c100f3ee9a59e4c
1 file changed