In __bswap16_var(), make sure the 16 upper bits are cleared; while

optimizing, gcc4 doesn't always do so.

Reported by:	Nathan Whitehorn
Approved by:	re (blanket)

sys/arm/include/endian.h

@@ -99,13 +99,15 @@ __bswap32_var(__uint32_t v)
 static __inline __uint16_t
 __bswap16_var(__uint16_t v)
 {
+	__uint32_t ret = v & 0xffff;
+
 	__asm __volatile(
 	    "mov    %0, %0, ror #8\n"
 	    "orr    %0, %0, %0, lsr #16\n"
 	    "bic    %0, %0, %0, lsl #16"
-	    : "+r" (v));
+	    : "+r" (ret));
 	
-	return (v);
+	return ((__uint16_t)ret);
 }		
 
 #ifdef __OPTIMIZE__