Fix ARM preprocessor macros in assembly.h

assembly.h defines some preprocessor macros for ARM assembly. However,
it would only do so if __ARM_FEATURE_CLZ was not already defined.
This change makes the ARM NaCl macro definitions independent of
__ARM_FEATURE_CLZ.

Bug: 1106311
Change-Id: I0df301ccdc55fd757c217fe1c73fd36e5d74c629
1 file changed