Use ccache so that it recompiles faster after a make clean.

Signed-off-by: franciscofranco <franciscofranco.1990@gmail.com>
Signed-off-by: Dan Trifan <jimsth@gmail.com>
Makefile: change build flags

Signed-off-by: Dan Trifan <jimsth@gmail.com>

Conflicts:
	Makefile
	arch/arm/Makefile
Makefile: remove 'mythical' build flags

1) The root's and the arch's Makefile do not both need to
contain the same build flags. The root's Makefile inherits
the arch's flags.

2) It is unnecessary to define the -mfpu=X flag, since the
arch's Makefile sets -msoft-float, which excludes the usage
of hardware vfp units.

3) Automatic vectorization via -ftree-vectorize does not
work with -msoft-float. Even if it were working, automatic
vectorization does not give noteworthy improvements in
performance.

4) In arch/arm/vfp/Makefile, it is counter-productive to
change the -mfpu=X assembler flag, since there's no hardware
vfp usable, as pointed out before.

Information sources:
  https://wiki.debian.org/ArmHardFloatPort/VfpComparison

  https://lkml.org/lkml/2011/10/3/254

Signed-off-by: Dan Trifan <jimsth@gmail.com>

Conflicts:
	arch/arm/vfp/Makefile
Makefile: Add Config Variable Os - O2 - O3 for choice Compilation

Conflicts:
	Makefile
 makefile: add config for graphite optimizations (synergydev)

makefile: add link-time optimization (synergydev)
makefile update

Conflicts:
	Makefile
Enable Optimization