netcdf: fix for ifort and missing f90 symbols

Netcdf when built with `--enable-fortran` using the Intel Fortran
compiler, ifort, does accept the `--force-load` option, causing a
build error where libnetcdff.dylib is missing all the f90 symbols.
The solution is in a FAQ on their website:
  Set lt_cv_ld_force_load=no

http://www.unidata.ucar.edu/software/netcdf/docs/known_problems.html#intel-fortran-macosx

Fixes #13050.
Closes #13174.

Signed-off-by: Charlie Sharpsteen <source@sharpsteen.net>

Library/Formula/netcdf.rb

@@ -35,7 +35,14 @@ def options
   end
 
   def install
-    ENV.fortran if fortran?
+    if fortran?
+      ENV.fortran
+      # fix for ifort not accepting the --force-load argument, causing
+      # the library libnetcdff.dylib to be missing all the f90 symbols.
+      # http://www.unidata.ucar.edu/software/netcdf/docs/known_problems.html#intel-fortran-macosx
+      # https://github.com/mxcl/homebrew/issues/13050
+      ENV['lt_cv_ld_force_load'] = 'no' if ENV['FC'] == 'ifort'
+    end
 
     common_args = %W[
       --disable-dependency-tracking