android: mesa: revert "Enable asm unconditionally"

This patch partially reverts 20294dce ("mesa: Enable asm unconditionally, ...")

Android makefile build logic needs to disable assembler optimization
in 32bit builds to avoid text relocations for libglapi.so shared

Fixes the following build error with Android x86 32bit target:

[  0% 4/477] target SharedLib: libglapi (out/target/product/x86/obj/SHARED_LIBRARIES/libglapi_intermediates/LINKED/libglapi.so)
FAILED: out/target/product/x86/obj/SHARED_LIBRARIES/libglapi_intermediates/LINKED/libglapi.so
...
prebuilts/gcc/linux-x86/x86/x86_64-linux-android-4.9/x86_64-linux-android/bin/ld: warning: shared library text segment is not shareable
prebuilts/gcc/linux-x86/x86/x86_64-linux-android-4.9/x86_64-linux-android/bin/ld: error: treating warnings as errors
clang-6.0: error: linker command failed with exit code 1 (use -v to see invocation)

Fixes: 20294dce ("mesa: Enable asm unconditionally, now that gen_matypes is gone.")
Signed-off-by: Mauro Rossi <issor.oruam@gmail.com>
Acked-by: Eric Engestrom <eric@engestrom.ch>
(cherry picked from commit 7a6e7803)