Use digit separators

Co-authored-by: Hubert Tong <[email protected]>

Author: jakeegan

compiler-rt/lib/sanitizer_common/sanitizer_platform.h

@@ -320,7 +320,7 @@
 
 // The first address that can be returned by mmap.
 #if SANITIZER_AIX && SANITIZER_WORDSIZE == 64
-#  define SANITIZER_MMAP_BEGIN 0x0a00000000000000ULL
+#  define SANITIZER_MMAP_BEGIN 0x0a00'0000'0000'0000ULL
 #else
 #  define SANITIZER_MMAP_BEGIN 0
 #endif