gcc40 f77 problem

[Doug Henry]

It seems the f77 support has changed to f95 support in gcc40.  Setting with_f77 will fail when building this package. Here are the changes I made to make it work:

- Changed f77 to f95 in the enable-languages option

- When f95 option is used the gmp package becomes a build requirement

- The default gmp package does not have MPFR support, so I modified gmp to have that option (--enable-mpfr)

- gcc40 cannot find gmp.h, so I added %{l_cppflags} the the CFLAGS list

happy compiling :-)