disable unaligned word access

* regint.h: disable unaligned word access with gcc 6 or later.
  [Bug #11831]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@53545 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

regint.h

@@ -48,6 +48,10 @@
 #endif
 #endif
 
+#if !defined(UNALIGNED_WORD_ACCESS) && defined(__GNUC__) && __GNUC__ >= 6
+# define UNALIGNED_WORD_ACCESS 0
+#endif
+
 #ifndef UNALIGNED_WORD_ACCESS
 #if defined(__i386) || defined(__i386__) || defined(_M_IX86) || \
     defined(__x86_64) || defined(__x86_64__) || defined(_M_AMD64) || \