[Support] Don't check MAP_ANONYMOUS, just use MAP_ANON

Though being marked "deprecated" by the Linux man-pages project
(MAP_ANON is a synonym of MAP_ANONYMOUS), it is the mostly widely
available macro - many systems that don't provide MAP_ANONYMOUS have
MAP_ANON. MAP_ANON is also used here and there in compiler-rt.

llvm-svn: 359758

Author: MaskRay

llvm/lib/Support/Unix/Memory.inc

@@ -93,14 +93,7 @@ Memory::allocateMappedMemory(size_t NumBytes,
 
   int fd = -1;
 
-  int MMFlags = MAP_PRIVATE |
-#ifdef MAP_ANONYMOUS
-  MAP_ANONYMOUS
-#else
-  MAP_ANON
-#endif
-  ; // Ends statement above
-
+  int MMFlags = MAP_PRIVATE | MAP_ANON;
   int Protect = getPosixProtectionFlags(PFlags);
 
 #if defined(__NetBSD__) && defined(PROT_MPROTECT)