Replace matrix.c(and its definitions) with linmath.h

[berylline]

Not sure if this would be an optimization or not, but it theoretically sounds like a nice idea anyway, at least.

matrix.c:

https://github.com/berylline/compiz/blob/master/src/matrix.c

compiz-core.h(where the functions in the above source file have header definitions):

https://github.com/berylline/compiz/blob/master/include/compiz-core.h#L3266

linmath.h:

https://github.com/datenwolf/linmath.h/blob/master/linmath.h