x86, asm: use bool for bitops and other assembly outputs

The gcc people have confirmed that using "bool" when combined with
inline assembly always is treated as a byte-sized operand that can be
assumed to be 0 or 1, which is exactly what the SET instruction
emits.  Change the output types and intermediate variables of as many
operations as practical to "bool".

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Link: http://lkml.kernel.org/r/1465414726-197858-3-git-send-email-hpa@linux.intel.com
Reviewed-by: Andy Lutomirski <luto@kernel.org>
Reviewed-by: Borislav Petkov <bp@suse.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>

arch/x86/include/asm/rmwcc.h

@@ -23,11 +23,11 @@ cc_label:								\
 
 #define __GEN_RMWcc(fullop, var, cc, ...)				\
 do {									\
-	char c;								\
+	bool c;								\
 	asm volatile (fullop "; set" cc " %1"				\
 			: "+m" (var), "=qm" (c)				\
 			: __VA_ARGS__ : "memory");			\
-	return c != 0;							\
+	return c;							\
 } while (0)
 
 #define GEN_UNARY_RMWcc(op, var, arg0, cc)				\