builtins: make ARM compilation with GAS work again

The LLVM IAS seems to accept wide instructions for add and sub in ARM mode even
though it is not permitted.  This uses a macro to ensure that the wide modifier
is only applied when building in THUMB mode.

This repairs building with GCC/GAS in ARM mode.

llvm-svn: 214046
diff --git a/compiler-rt/lib/builtins/arm/udivsi3.S b/compiler-rt/lib/builtins/arm/udivsi3.S
index 7086a44..bb5f8a0 100644
--- a/compiler-rt/lib/builtins/arm/udivsi3.S
+++ b/compiler-rt/lib/builtins/arm/udivsi3.S
@@ -112,8 +112,8 @@
 #define block(shift)                                                           \
 	cmp	r0, r1, lsl IMM shift;                                         \
 	ITT(hs);                                                               \
-	addhs.w	r3, r3, IMM (1 << shift);                                      \
-	subhs.w	r0, r0, r1, lsl IMM shift
+	WIDE(addhs)	r3, r3, IMM (1 << shift);                              \
+	WIDE(subhs)	r0, r0, r1, lsl IMM shift
 
 	block(31)
 	block(30)