userland: add assembly support

Move arm assembly cheat here, and start some work on x86 cheat as well.

userland/arch/arm/s_suffix.S

@@ -0,0 +1,35 @@
+/* https://github.com/cirosantilli/arm-assembly-cheat#s-suffix */
+
+#include "common.h"
+
+ENTRY
+
+    /* Result is 0, set beq. */
+    movs r0, 0
+    ASSERT(beq)
+
+    /* The opposite. */
+    movs r0, 1
+    ASSERT(bne)
+
+    /* mov without s does not set the status. */
+    movs r0, 0
+    mov r0, 1
+    ASSERT(beq)
+
+    /* movs still moves... */
+    mov r0, 0
+    movs r0, 1
+    ASSERT_EQ(r0, 1)
+
+    /* add: the result is 0. */
+    mov r0, 1
+    adds r0, -1
+    ASSERT(beq)
+
+    /* add: result non 0. */
+    mov r0, 1
+    adds r0, 1
+    ASSERT(bne)
+
+EXIT