arm: fix setjmp and longjmp asm for armv8-a

armv8 removed the coprocessor instructions other than cp14, so
on an armv8 system the related hwcaps should never be set.

new llvm complains about the use of coprocessor instructions in
armv8-a mode (even though they are never executed at runtime),
so ifdef them out when musl is built for armv8.

src/setjmp/arm/longjmp.s → src/setjmp/arm/longjmp.S

@@ -16,11 +16,14 @@ longjmp:
 	ldr r2,1f
 	ldr r1,[r1,r2]
 
+#if __ARM_ARCH < 8
 	tst r1,#0x260
 	beq 3f
+	// HWCAP_ARM_FPA
 	tst r1,#0x20
 	beq 2f
 	ldc p2, cr4, [ip], #48
+#endif
 2:	tst r1,#0x40
 	beq 2f
 	.fpu vfp
@@ -28,6 +31,8 @@ longjmp:
 	.fpu softvfp
 	.eabi_attribute 10, 0
 	.eabi_attribute 27, 0
+#if __ARM_ARCH < 8
+	// HWCAP_ARM_IWMMXT
 2:	tst r1,#0x200
 	beq 3f
 	ldcl p1, cr10, [ip], #8
@@ -36,6 +41,8 @@ longjmp:
 	ldcl p1, cr13, [ip], #8
 	ldcl p1, cr14, [ip], #8
 	ldcl p1, cr15, [ip], #8
+#endif
+2:
 3:	bx lr
 
 .hidden __hwcap

src/setjmp/arm/setjmp.s → src/setjmp/arm/setjmp.S

@@ -18,11 +18,14 @@ setjmp:
 	ldr r2,1f
 	ldr r1,[r1,r2]
 
+#if __ARM_ARCH < 8
 	tst r1,#0x260
 	beq 3f
+	// HWCAP_ARM_FPA
 	tst r1,#0x20
 	beq 2f
 	stc p2, cr4, [ip], #48
+#endif
 2:	tst r1,#0x40
 	beq 2f
 	.fpu vfp
@@ -30,6 +33,8 @@ setjmp:
 	.fpu softvfp
 	.eabi_attribute 10, 0
 	.eabi_attribute 27, 0
+#if __ARM_ARCH < 8
+	// HWCAP_ARM_IWMMXT
 2:	tst r1,#0x200
 	beq 3f
 	stcl p1, cr10, [ip], #8
@@ -38,6 +43,8 @@ setjmp:
 	stcl p1, cr13, [ip], #8
 	stcl p1, cr14, [ip], #8
 	stcl p1, cr15, [ip], #8
+#endif
+2:
 3:	bx lr
 
 .hidden __hwcap