Use correct __ARM_ARCH macro

git-svn-id: https://llvm.org/svn/llvm-project/libcxxabi/trunk@217341 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/src/Unwind/UnwindRegistersRestore.S b/src/Unwind/UnwindRegistersRestore.S
index 362a5b0..5fdb789 100644
--- a/src/Unwind/UnwindRegistersRestore.S
+++ b/src/Unwind/UnwindRegistersRestore.S
@@ -326,7 +326,7 @@
   ldm lr, {r0-r12}
   ldr sp, [lr, #52]
   ldr lr, [lr, #60]  @ restore pc into lr
-#if _ARM_ARCH > 4
+#if __ARM_ARCH > 4
   bx lr
 #else
   mov pc, lr
diff --git a/src/Unwind/UnwindRegistersSave.S b/src/Unwind/UnwindRegistersSave.S
index d23c816..1e988e2 100644
--- a/src/Unwind/UnwindRegistersSave.S
+++ b/src/Unwind/UnwindRegistersSave.S
@@ -304,7 +304,7 @@
   str lr, [r0, #56]
   str lr, [r0, #60]  @ store return address as pc
   mov r0, #0         @ return UNW_ESUCCESS
-#if _ARM_ARCH > 4
+#if __ARM_ARCH > 4
   bx lr
 #else
   mov pc, lr