build: update compile.sh to support bsd systems

On FreeBSD /usr used by base system, use PREFIX=/usr/local instead.
On BSD systems gnu "make" has the name "gmake".

Signed-off-by: Oliver Pinter <oliver.pntr@gmail.com>
build: switch from hardcoded gcc to default c compiler

	modified:   Makefile

Signed-off-by: Oliver Pinter <oliver.pntr@gmail.com>
build: switch from hardcoded gcc to default c compiler

	modified:   tests/Makefile

Signed-off-by: Oliver Pinter <oliver.pntr@gmail.com>
info: update COMPILE

	modified:   COMPILE

Signed-off-by: Oliver Pinter <oliver.pntr@gmail.com>