[ubsan] Use internal_memcpy to copy ubsan bits size (#121586)

While fetching amounts of bits used to correctly display ubsan value
reinterpret_cast was used, however as noted by Jakub Jelínek in
#96240 discussion it might
cause issues due to potentially unaligned memory access. The patch
addresses this problem.

Co-authored-by: Vladislav Aranov <[email protected]>

Author: earnol

compiler-rt/lib/ubsan/ubsan_value.h

@@ -150,9 +150,12 @@ class TypeDescriptor {
 
   unsigned getIntegerBitCount() const {
     DCHECK(isIntegerTy());
-    if (isSignedBitIntTy())
-      return *reinterpret_cast<const u32 *>(getBitIntBitCountPointer());
-    else
+    if (isSignedBitIntTy()) {
+      u32 BitCountValue;
+      internal_memcpy(&BitCountValue, getBitIntBitCountPointer(),
+                      sizeof(BitCountValue));
+      return BitCountValue;
+    } else
       return getIntegerBitWidth();
   }