Replace bx lr with update of pc from the stack.

When there is arm assembler of this format:

ldmxx sp!, {..., lr} or pop {..., lr}
bx lr

It can be replaced with:

ldmxx sp!, {..., pc} or pop {..., pc}

Change-Id: Ic27048c52f90ac4360ad525daf0361a830dc22a3
diff --git a/libc/arch-arm/generic/bionic/memset.S b/libc/arch-arm/generic/bionic/memset.S
index d17a9c4..b8eabbf 100644
--- a/libc/arch-arm/generic/bionic/memset.S
+++ b/libc/arch-arm/generic/bionic/memset.S
@@ -82,8 +82,7 @@
         strbcs      r1, [r0], #1
         strbmi      r1, [r0], #1
         subs        r2, r2, r3
-        popls       {r0, r4-r7, lr}    /* return */
-        bxls        lr
+        popls       {r0, r4-r7, pc}    /* return */
 
         /* align the destination to a cache-line */
         mov         r12, r1
@@ -126,8 +125,7 @@
         strhmi      r1, [r0], #2
         movs        r2, r2, lsl #2
         strbcs      r1, [r0]
-        ldmfd       sp!, {r0, r4-r7, lr}
-        bx          lr
+        ldmfd       sp!, {r0, r4-r7, pc}
 END(memset)
 
         .data