8361433: [Big Endian] assert(verify_guards()) failed: Expected valid memory guards after 8357601

Author: TheRealMDoerr

src/hotspot/share/memory/guardedMemory.hpp

@@ -119,7 +119,7 @@ class GuardedMemory : StackObj { // Wrapper on stack
         // We may not be able to dereference directly so use
         // SafeFetch. It doesn't matter if the value read happens
         // to be 0xFF as that is not what we expect anyway.
-        u_char val = (u_char) SafeFetch32((int*)c, 0xFF);
+        u_char val = (u_char) (SafeFetch32((int*)c, 0xFF) BIG_ENDIAN_ONLY(>> 24));
         if (val != badResourceValue) {
           return false;
         }