lib, isa-l: solve build error of isa-l

This patch solves build problem at least on Gentoo[1] and solves
ignoring some enviroment variables like CC. Patch solves
- hardcoding compiler to gcc instead use CC enviroment variable
- ignoring CFLAGS
- build error caused by passing incorrect macro name to compiler
- unconditionally striping library, now isa-l library isn't striped
- executable stack
- turn on more verbose building, now invocation of compiler isn't
  hidden

[1] - http://lists.wpkg.org/pipermail/sheepdog-users/2014-November/002807.html

Signed-off-by: Marcin Mirosław <marcin@mejor.pl>
Signed-off-by: Hitoshi Mitake <mitake.hitoshi@lab.ntt.co.jp>