[asan] flatten the asan-rt build slightly

llvm-svn: 145631
diff --git a/compiler-rt/lib/asan/asan_malloc_linux.cc b/compiler-rt/lib/asan/asan_malloc_linux.cc
index 1b96714..9dbc7a1 100644
--- a/compiler-rt/lib/asan/asan_malloc_linux.cc
+++ b/compiler-rt/lib/asan/asan_malloc_linux.cc
@@ -13,6 +13,7 @@
 // We simply define functions like malloc, free, realloc, etc.
 // They will replace the corresponding libc functions automagically.
 //===----------------------------------------------------------------------===//
+#ifdef __linux__
 
 #include "asan_allocator.h"
 #include "asan_interceptors.h"
@@ -137,3 +138,5 @@
   return asan_pvalloc(size, &stack);
 }
 }  // extern "C"
+
+#endif  // __linux__