arm/arch_string.S: Only use sane insns for Clang

src/system/libroot/posix/string/arch/arm/arch_string.S

@@ -115,6 +115,7 @@ FUNCTION(memcpy):
 	msr		CPSR_f, r12				// move into NZCV fields in CPSR
 
 	// move as many bytes as necessary to get the dst aligned
+#ifdef __clang__
 	ldrbvs	r3, [r1], #1			// V set
 	ldrhcs	r4, [r1], #2			// C set
 	ldreq	r5, [r1], #4			// Z set
@@ -125,6 +126,18 @@ FUNCTION(memcpy):
 
 	ldmiami	r1!, {r3-r4}			// N set
 	stmiami	r0!, {r3-r4}
+#else
+	ldrvsb	r3, [r1], #1			// V set
+	ldrcsh	r4, [r1], #2			// C set
+	ldreq	r5, [r1], #4			// Z set
+
+	strvsb	r3, [r0], #1
+	strcsh	r4, [r0], #2
+	streq	r5, [r0], #4
+
+	ldmmiia r1!, {r3-r4}			// N set
+	stmmiia r0!, {r3-r4}
+#endif
 
 	// fix the remaining len
 	sub		r2, r2, r12, lsr #28