cmake: Always use user defined CFLAGS, not only for release builds

[xdustinface]

No description provided.

[dfaranha]

Hi, I've thought about this before. The point is to build with release flags AND debugging symbols?

[xdustinface]

Hey,

the reason for this PR is that we need to provide custom flags for includes also in debug build. I guess an other option would be to always pass the existing environment CFLAGS through. Maybe something like:

if(DEBUG)
	set(CFLAGS "-O0 -fno-omit-frame-pointer $ENV{CFLAGS}" CACHE STRING)
	set(DFLAGS "-ggdb")
else()
	set(CFLAGS "-O2 -funroll-loops -fomit-frame-pointer $ENV{CFLAGS}" CACHE STRING)
endif()

Didn't test this ^ but i guess i should work. But my feeling says just having the option to fully take control of the flags is better? Thoughts?

EDIT: Hmm.. just might be confusing that the DEBUG option has no impact if custom CFLAGS are used then.
EDIT2: We could though throw an error then if DEBUG is used together with custom CFLAGS?

[xdustinface]

@dfaranha any thoughts about the above?

[dfaranha]

I think it makes sense and DEBUG might just enable debugging symbols when custom CFLAGs are passed. I will merge and do some minor adjustments tonight, after I give some testing. Last time I played with CFLAGS I broke a few projects depending on RELIC. :)

[dfaranha]

Merged with a tiny adjustment! Hope it does not break builds elsewhere :)