Use unified syntax to compile with both llvm and gcc.

All arch-arm and arch-arm64 .S files were compiled
by gcc with and without this patch. The output object files
were identical. When compiled with llvm and this patch,
the output files were also identical to gcc's output.

BUG: 18061004
Change-Id: I458914d512ddf5496e4eb3d288bf032cd526d32b
diff --git a/libc/arch-arm/krait/bionic/memset.S b/libc/arch-arm/krait/bionic/memset.S
index e9f6431..a4fbe17 100644
--- a/libc/arch-arm/krait/bionic/memset.S
+++ b/libc/arch-arm/krait/bionic/memset.S
@@ -37,6 +37,7 @@
  */
 
     .fpu    neon
+    .syntax unified
 
 ENTRY(__memset_chk)
         cmp         r2, r3
@@ -98,9 +99,9 @@
 1:      bge         2f
         vst1.32     {d0[0]}, [r0]!
 2:      movs        ip, r2, lsl #31
-        strmib      r1, [r0], #1
-        strcsb      r1, [r0], #1
-        strcsb      r1, [r0], #1
+        strbmi      r1, [r0], #1
+        strbcs      r1, [r0], #1
+        strbcs      r1, [r0], #1
         ldmfd       sp!, {r0}
         bx          lr
 END(memset)