NFC: Ignore deprecation of asl_log in the runtime and demangling library.

ASL is deprecated in macOS 10.12. It may be time to transition to os_log now
that deployment targets have been raised to 10.12, but until that project
starts these warnings are just pollution.

Filed rdar://121066531 to track adoption of `os_log()` if appropriate.

stdlib/public/LLVMSupport/ErrorHandling.cpp

@@ -41,7 +41,10 @@ void error(const char *prefix, const char *msg, const char *file = nullptr, unsi
   }
 
 #if SWIFT_STDLIB_HAS_ASL
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wdeprecated-declarations"
   asl_log(nullptr, nullptr, ASL_LEVEL_ERR, "%s", buffer);
+#pragma clang diagnostic pop
 #elif defined(__ANDROID__) && !defined(__TERMUX__)
   __android_log_print(ANDROID_LOG_FATAL, "SwiftRuntime", "%s", buffer);
 #elif defined(_WIN32)