android: Re-enable optimization
android: Re-enable optimization

The introduction of $(EXTRA_CFLAGS) in commit 00f0b80e4befe4
("android: Build ARM with -march=armv7-a") inadvertently overrode the
default "-O2 -g" CFLAGS.  Fixing this + enabling Thumb reduces the ARM
libopenconnect.so from ~3.5MB to ~1.9MB.

Signed-off-by: Kevin Cernekee <3105dbb3dd63fbb4f6371cfb04adc6726f76c56b@gmail.com>

cernekee/openconnect,cernekee/openconnect,cernekee/openconnect,cernekee/openconnect