minimal: Add a few more compiler options to slim down native exe size.
minimal: Add a few more compiler options to slim down native exe size.

Nowadays compilers come with quite a bloaty options enabled by default,
so disable them all down.

With this setup, MICROPY_ENABLE_COMPILER=0 build for x86_32 is finally
well below 64K (~62K).

Change-Id: Iab7bcc868e7992420b066305329aea5b2752f96e

pfalcon/micropython,pfalcon/micropython,pfalcon/micropython,pfalcon/micropython,pfalcon/micropython