FortranCInterface: Use CMake 2.8.0 behavior

The FortranCInterface module should execute with CMake 2.8.0 behavior
even if policies are set differently by the including project.  In
particular, it makes use of empty list elements and therefore expects
NEW behavior of CMP0007.

Modules/FortranCInterface.cmake

@@ -100,6 +100,10 @@ if(FortranCInterface_SOURCE_DIR)
   return()
 endif()
 
+# Use CMake 2.8.0 behavior for this module regardless of including context.
+cmake_policy(PUSH)
+cmake_policy(VERSION 2.8.0)
+
 #-----------------------------------------------------------------------------
 # Verify that C and Fortran are available.
 foreach(lang C Fortran)
@@ -273,3 +277,6 @@ function(FortranCInterface_VERIFY)
       "The output was:\n  ${_output}")
   endif()
 endfunction()
+
+# Restore including context policies.
+cmake_policy(POP)