Test which flags make our asm compile.

Previously we relied on assumption that clang always needs -no-integrated-as
but it's not always true.

asm-tests/arm.S

@@ -0,0 +1,20 @@
+/* on arm clang doesn't support .arch directive */
+
+	.text
+	.syntax	unified
+
+#if !defined (__thumb2__)
+	.arch	armv7a
+	.arm
+#else
+	.arch	armv7
+	.thumb
+#endif
+	mcr	p15, 0, r11, c7, c14, 2
+
+	/* clang restricts access to dsb/isb despite .arch  */
+	dsb
+	isb
+
+
+	

asm-tests/i386.S

@@ -0,0 +1,10 @@
+/* on x86 old clang doesn't support .code16
+   newer clang supports it but creates 6-byte jumps instead of 3-byte ones
+   which makes us go over boot sector size.  */
+
+	.code16
+	jmp far
+	.org 4
+	.space 300
+far:
+	.byte 0

asm-tests/mips.S

@@ -0,0 +1,11 @@
+/* on mips clang doesn't support privilegied instructions, doubleword store/load
+   and crashes with hand-written assembly
+ */
+
+	.set mips3
+	sync
+	ld $t2, 0($t6)
+
+a:
+	addiu $t7, $s0, (b - a)
+b:	nop

asm-tests/powerpc.S

@@ -0,0 +1,8 @@
+/* clang <= 3.3 doesn't handle most of ppc assembly, not even inline assembly
+   used by gcrypt */
+/* Cache invalidation loop is a fair test.  */
+	li 5, 0
+1:	icbi 5, 3
+	addi 5, 5, 32
+	cmpw 5, 4
+	blt 1b

asm-tests/sparc64.S

@@ -0,0 +1,9 @@
+        .text
+1:	
+	/* A small list of examples of what clang doesn't support.  */
+	clr	%o0
+	lduw	[%o4 + 4], %o4
+	and     %o6, ~0xff, %o6
+	stw	%o5, [%o3]
+	bne,pt	%icc, 1b
+	 nop