[scudo] Check if we use __clang_major__ >= 12

This makes sure we have support for MTE instructions.
Later the check can be extended to support MTE on other compilers.

Reviewed By: pcc

Differential Revision: https://reviews.llvm.org/D105722

Author: vitalybuka

compiler-rt/lib/scudo/standalone/memtag.h

@@ -18,7 +18,7 @@
 
 namespace scudo {
 
-#if defined(__aarch64__) || defined(SCUDO_FUZZ)
+#if (__clang_major__ >= 12 && defined(__aarch64__)) || defined(SCUDO_FUZZ)
 
 // We assume that Top-Byte Ignore is enabled if the architecture supports memory
 // tagging. Not all operating systems enable TBI, so we only claim architectural
@@ -55,7 +55,7 @@ inline uint8_t extractTag(uptr Ptr) {
 
 #endif
 
-#if defined(__aarch64__)
+#if __clang_major__ >= 12 && defined(__aarch64__)
 
 #if SCUDO_LINUX