compiler-rt: remove unnecessary include

This is to sync the code with upstream, see:
See llvm/llvm-project#73439 (comment)

Fixes:		4c9a0ad
MFC after:	3 days

(cherry picked from commit d203302)

Author: DimitryAndric

contrib/llvm-project/compiler-rt/lib/sanitizer_common/sanitizer_linux_libcdep.cpp

@@ -47,7 +47,6 @@
 
 #if SANITIZER_FREEBSD
 #include <pthread_np.h>
-#include <stdlib.h>
 #include <osreldate.h>
 #include <sys/auxv.h>
 #include <sys/sysctl.h>