Use new Autoconf 2.69 Fortran m4 macros

[ompiteam]

AC 2.69 introduced some new Fortran macros that could be quite helpful (and replace some kludgery that we currently have):

• AC_F77_IMPLICIT_NONE and AC_FC_IMPLICIT_NONE to disable implicit integer
• AC_FC_MODULE_EXTENSION to compute the Fortran 90 module name extension
• AC_FC_MODULE_FLAG for the Fortran 90 module search path flag
• AC_FC_MODULE_OUTPUT_FLAG for the Fortran 90 module output directory flag
• AC_FC_PP_SRCEXT for preprocessed Fortran source files extensions
• AC_FC_PP_DEFINE for the Fortran preprocessor define flag

Once we upgrade the minimum requirement of Autoconf in OMPI, we should start using these macros.

[ompiteam]

Imported from trac issue 3083. Created by jsquyres on 2012-04-25T09:56:00, last modified: 2013-07-16T12:09:33