To build:

1) WRFV2 should already be compiled, so that gridgen_model can be built 
   with the IO API implementations in WRF's external directory. Given
   a compiled version of WRFV2, change gridgen's top-level Makefile by 
   setting the value of WRF_DIR to the location of the WRFV2 directory.

2) Ensure that the values of FC and CC for the target machine in the 
   top-level Makefile are set to the compilers used to build WRFV2. 

3) Type 'make'. If a symbolic link to src/gridgen_model.exe appears in 
   the top-level directory, the compilation was successful.