setup.py: allow to override extra_compile_args

[giuliobenetti]

At the moment extra_compile_args is set to -O2 by default. But m68k toolchain has a bug that when trying to build Extension uvloop.loop enters an infinite loop1. So we need to override -O2 with -O0 to make it work. So let's getenv('MODULES_CFLAGS') and assign it to local MODULES_CFLAGS (former CFLAGS) and assign it to extra_compile_args. If not MODULES_CFLAGS is found then -O2 is kept as default.

Signed-off-by: Giulio Benetti [email protected]

[fantix]

Thanks for the PR! I renamed the env to UVLOOP_OPT_CFLAGS