autotools, preprocessors, and fortran 90

Hi,

I don't know if this is the right place for this question, but ...

I'm trying to set up a small fortran 90 project using the gnu
auto-tools.  My fortran files (*.f90) require a preprocessor to
interpret # directives.  In the case of gcc, I need to add the flag -x
f95-cpp-input to force the use of the preprocessor.  I can do this
by adding the line

AM_FCFLAGS = -x f95-cpp-input

to Makefile.am.  I have two problems with this. One, it will only work
with compilers that accept this flag, e.g., gcc.  Two, it also gets
passed to the linker, which requires fiddling with the linker flags.

Any ideas on what the best way to handle this problem is?  (I'm a
beginner with using the gnu autotools.)

Thanks,
John