sage ignores some environment variables

[dfdeshom]

Reported by Gonzalo Tornaria:

Ideally, it would be nice to (e.g)

export CC=gcc-4.3
export CXX=g++-4.3
export F77=gfortran-4.3

then build sage, and have it *consistently* use the compilers as set
in the environment variables. This doesn't quite work, because at some
points the compilation just ignores the env variables. Below there is
a list of the obstructions I found for this to work.


A) sage-spkg itself, for logging, calls "gcc -v", instead of "${CC-gcc} -v".

Easy fix:
---------------------------------------------------------------
--- a/sage-spkg Mon Apr 21 01:43:53 2008 -0700
+++ b/sage-spkg Tue Apr 22 12:37:48 2008 -0300
@@ -241,8 +241,8 @@

 echo "****************************************************"
 echo "GCC Version"
-echo "gcc -v"
-gcc -v
+echo "${CC-gcc} -v"
+${CC-gcc} -v
 if [ $? -ne 0 ]; then
   echo "Unable to determine gcc version."
 fi
---------------------------------------------------------------

B) sage-env, tests if CC is gcc, which means "CC=gcc-4.3" might not
work exactly the same as if gcc is a symlink to gcc-4.3, for instance:

if [ "$SAGE64" = "yes" -a CC = "gcc" ]; then
  CFLAGS="$CFLAGS -m64"
fi

C) packages which seem to not honor CC environment variable (they use "gcc"):

flint-1.06.p2
atlas-3.8.1.p1
f2c-20070816.p0
symmetrica-2.0.p2
polybori-0.3.1.p1
rubiks-20070912.p5
zn_poly-0.8.p0
sage-3.0.rc1
gap-4.4.10.p7 // guava3.4
tachyon-0.98beta.p5
palp-1.1.p1

(gap itself uses CC, but compilation of guava, which is part of gap
spkg, does not).

D) packages which seem not to honor CXX environment variable (they use "g++")

polybori-0.3.1.p1
rubiks-20070912.p5
sage-3.0.rc1
gfan-0.3.p3
flintqs-20070817.p3


E) fortran

Just for the record, a lot of configure scripts seem to check for
fortran, even if they don't use it. It appears the relevant
environment variables are F77 and FFLAGS. Anyway, the variable
SAGE_FORTRAN seems to be honored fine for the packages that actually
need fortran.

[dfdeshom]

I'm marking this as duplicate, since I've broken it down to #2999, #3000, #3001, #3002