Fortran: Add compiler ID/Version generator expressions
Adds Fortran_COMPILER_ID
and Fortran_COMPILER_VERSION
generator
expression support to match equivalent C_COMPILER_ID
,
CXX_COMPILER_ID
, C_COMPILER_VERSION
, and CXX_COMPILER_VERSION
support.
This is very helpful in the case where the C/C++ compiler suite is a
different type of compiler from the platform Fortran compiler and
projects use generator expressions to assign compiler flags and
definitions. (e.g. GNU
C/C++ and SunPro
Fortran on Linux)