[Patch, Fortran + Testsuite] Fix coarray handling in modules

[Dominique Dhumieres]

Happy New Year to all.

The test gfortran.dg/coarray/codimension_2.f90 fails on x86_64-apple-darwin14 with -m32
(see https://gcc.gnu.org/ml/gcc-testresults/2015-01/msg00185.html). The error is

gfc /opt/gcc/work/gcc/testsuite/gfortran.dg/coarray/codimension_2.f90 /opt/gcc/work/gcc/testsuite/gfortran.dg/coarray/codimension_2a.f90 -fcoarray=lib -O2 -lcaf_single -m32
/var/folders/8q/sh_swgz96r7f5vnn08f7fxr00000gn/T//ccPcznrm.s:18:non-relocatable subtraction expression, "__F.caf_token__global_coarrays_MOD_b" minus "L1$pb"
/var/folders/8q/sh_swgz96r7f5vnn08f7fxr00000gn/T//ccPcznrm.s:18:symbol: "__F.caf_token__global_coarrays_MOD_b" can't be undefined in a subtraction expression

Dominique