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/generic/bionic/memset.S b/libc/arch-arm/generic/bionic/memset.S
index be35de9..d17a9c4 100644
--- a/libc/arch-arm/generic/bionic/memset.S
+++ b/libc/arch-arm/generic/bionic/memset.S
@@ -35,6 +35,8 @@
          * memset() returns its first argument.
          */
 
+         .syntax unified
+
 ENTRY(__memset_chk)
         cmp         r2, r3
         bls         done
@@ -76,11 +78,11 @@
         orr         r1, r1, r1, lsr #16
 
         movs        r12, r3, lsl #31
-        strcsb      r1, [r0], #1    /* can't use strh (alignment unknown) */
-        strcsb      r1, [r0], #1
-        strmib      r1, [r0], #1
+        strbcs      r1, [r0], #1    /* can't use strh (alignment unknown) */
+        strbcs      r1, [r0], #1
+        strbmi      r1, [r0], #1
         subs        r2, r2, r3
-        ldmlsfd     sp!, {r0, r4-r7, lr}    /* return */
+        popls       {r0, r4-r7, lr}    /* return */
         bxls        lr
 
         /* align the destination to a cache-line */
@@ -100,9 +102,9 @@
 
         /* conditionally writes 0 to 7 words (length in r3) */
         movs        r3, r3, lsl #28
-        stmcsia     r0!, {r1, lr}
-        stmcsia     r0!, {r1, lr}
-        stmmiia     r0!, {r1, lr}
+        stmcs       r0!, {r1, lr}
+        stmcs       r0!, {r1, lr}
+        stmmi       r0!, {r1, lr}
         movs        r3, r3, lsl #2
         strcs       r1, [r0], #4
 
@@ -117,13 +119,13 @@
 
         /* conditionally stores 0 to 31 bytes */
         movs        r2, r2, lsl #28
-        stmcsia     r0!, {r1,r3,r12,lr}
-        stmmiia     r0!, {r1, lr}
+        stmcs       r0!, {r1,r3,r12,lr}
+        stmmi       r0!, {r1, lr}
         movs        r2, r2, lsl #2
         strcs       r1, [r0], #4
-        strmih      r1, [r0], #2
+        strhmi      r1, [r0], #2
         movs        r2, r2, lsl #2
-        strcsb      r1, [r0]
+        strbcs      r1, [r0]
         ldmfd       sp!, {r0, r4-r7, lr}
         bx          lr
 END(memset)