Use MAKE variable instead of 'make'

Fix the last two occurrences of 'make' in the Makefiles to use the MAKE
variable instead. Fixes:

warning: jobserver unavailable: using -j1.  Add `+' to parent make rule.
Resize ic_maxs.png to 128x128

from the original 512x512 ic_maxs.svg
Make 'distclean' not invoke git-clean
Add scripts/removemodules.sh