Respect CC and CFLAGS in Makefiles

[mmokrejs]

Hi Gregory,
I wanted to create a package for Gentoo Linux but I will need to edit your Makefiles (tested current git master). Few comments what you may want to change:

Use CC ?= gcc, likewise CFLAGS ?= -blah. It is not good you overwrite users CC/CXX/CFLAGS/CXXFLAGS values.

Umm, actually the problem is that you use CCFLAGS instead of CFLAGS variable:

CCFLAGS := -Wall -O3 -D COMPILE_USER_MODE -D BUILDNUM=$(BUILDNUM)

You probably want to first check if it is empty, then add to it -Wall -O3. After that, append to it -D COMPILE_USER_MODE -D BUILDNUM=$(BUILDNUM).

Same applies to sambamba. ;-)
Hope this helps.

[jlec]

Fix is in PR #6