[Patch, fortran] Runtime memory leak checking.

[Dominique Dhumieres]

> (1) I think the -static option won't work on Darwin.

Confirmed: I get

[ibook-dhum] f90/bug% gfc -static -fruntime-check=memleaks /opt/gcc/gcc-4.4-work/gcc/testsuite/gfortran.dg/mem_check_1.f90 -L/opt/gcc/gcc4.4w/lib/ 
ld_classic: can't locate file for: -lcrt0.o
collect2: ld returned 1 exit status

without the -static option, I can compile, but I get at runtime:

[ibook-dhum] f90/bug% gfc -fruntime-check=memleaks /opt/gcc/gcc-4.4-work/gcc/testsuite/gfortran.dg/mem_check_1.f90
[ibook-dhum] f90/bug% a.out 
dyld: Symbol not found: _htab_hash_pointer
  Referenced from: /opt/gcc/gcc4.4w/lib/libgfortran.3.dylib
  Expected in: dynamic lookup

Trace/BPT trap

TIA

Dominique