Makefile: add CCACHE
Add CCACHE to Makefile to make secondary builds faster, this is just like enabling ccache in ROM builds.
This should "Theoretically" lessen builds times by 30 - 40%, tested it and it does make the build faster.

Original commit: https://github.com/jfdsmabalot/kernel_hammerhead/commit/14e6e5e7d0423f156a8c085c66af0fff4488f5f2

Signed-off-by: Jean Francis Dominique S. Mabalot <jfdsmabalot@redhat.com>