[builtins] Fix assembly in arm sync-ops.h

This assembly is part of a macro that was reformatted in D60351.
The missing space between push and { results in:

    Error: bad instruction `push{r4, r5,r6,lr}'

llvm-svn: 365957

Author: nikic

compiler-rt/lib/builtins/arm/sync-ops.h

@@ -34,7 +34,7 @@
   .thumb;                                                                      \
   .syntax unified;                                                             \
   DEFINE_COMPILERRT_THUMB_FUNCTION(__sync_fetch_and_##op)                      \
-  push{r4, r5, r6, lr};                                                        \
+  push {r4, r5, r6, lr};                                                       \
   dmb;                                                                         \
   mov r12, r0;                                                                 \
   LOCAL_LABEL(tryatomic_##op) : ldrexd r0, r1, [r12];                          \