fortify: allow diagnostics without run-time checks (attempt #2)

In configs like ASAN, we can't use _chk functions. This CL builds off of
previous work to allow us to still emit diagnostics in conditions like
these.

Wasn't 100% sure what a good test story would look like here. Opinions
appreciated.

Bug: 141267932
Test: checkbuild on internal-master. TreeHugger for x86_64.
Change-Id: I65da9ecc9903d51a09f740e38ab413b9beaeed88
diff --git a/libc/include/bits/fortify/stat.h b/libc/include/bits/fortify/stat.h
index 6a2e822..43fc69c 100644
--- a/libc/include/bits/fortify/stat.h
+++ b/libc/include/bits/fortify/stat.h
@@ -41,11 +41,11 @@
     __overloadable
     __enable_if(1, "")
     __clang_error_if(mode & ~0777, "'umask' called with invalid mode") {
-#if __ANDROID_API__ >= __ANDROID_API_J_MR2__
+#if __ANDROID_API__ >= __ANDROID_API_J_MR2__ && __BIONIC_FORTIFY_RUNTIME_CHECKS_ENABLED
   return __umask_chk(mode);
 #else
   return __umask_real(mode);
-#endif  /* __ANDROID_API__ >= __ANDROID_API_J_MR2__ */
+#endif
 }
 
 #endif /* defined(__BIONIC_FORTIFY) */