Add support for Intel Fortran compilers.

Port changes from upstream Reference-LAPACK.

cmake/fc.cmake

@@ -67,7 +67,15 @@ if (${F_COMPILER} STREQUAL "GFORTRAN")
     if (BINARY64)
       set(FCOMMON_OPT "${FCOMMON_OPT} -m64")
       if (INTERFACE64)
-        set(FCOMMON_OPT "${FCOMMON_OPT} -fdefault-integer-8")
+        if (CMAKE_Fortran_COMPILER_ID STREQUAL "Intel")
+          if (WIN32)
+            set(FCOMMON_OPT "${FCOMMON_OPT} /integer-size:64")
+          else ()
+            set(FCOMMON_OPT "${FCOMMON_OPT} -integer-size 64")
+          endif ()
+        else ()
+          set(FCOMMON_OPT "${FCOMMON_OPT} -fdefault-integer-8")
+        endif ()
       endif ()
     else ()
       set(FCOMMON_OPT "${FCOMMON_OPT} -m32")