#110 configure: accept CFLAGS CXXFLAGS CCASFLAGS settings

[Jack Thomasson]

i'm compiling on a x86_64 host which must be
restricted to 32 bit for cpu=jitc_x86 so the required
-m32 parameter must be passed in CFLAGS, CXXFLAGS and
CCASFLAGS. the attached patch:
* honors setting CFLAGS, CXXFLAGS and CCASFLAGS
for all combinations of
-{dis,en}able-{debug,release}
* default CXXFLAGS and CCASFLAGS to CFLAGS
* pass CCASFLAGS down to sub-Makefile

i invoke this incantation to build PearPC on SuSE
10.0:

configure --enable-cpu=jitc_x86 \
--x-includes=/usr/X11R6/include \
--x-libraries=/usr/X11R6/lib \
--target=i686-unknown-linux \
--program-transform=s,y,y, \
CFLAGS=-m32

[Jack Thomasson]

patch configure.in to accept CFLAGS CXXFLAGS CCASFLAGS settings