Update fc.cmake

cmake/fc.cmake

@@ -88,7 +88,9 @@ if (${F_COMPILER} STREQUAL "GFORTRAN" OR ${F_COMPILER} STREQUAL "F95" OR CMAKE_F
     endif ()
   else ()
     if (BINARY64)
+      if (NOT CMAKE_Fortran_COMPILER_ID MATCHES "LLVMFlang.*")
       set(FCOMMON_OPT "${FCOMMON_OPT} -m64")
+      endif ()
       if (INTERFACE64)
         if (CMAKE_Fortran_COMPILER_ID STREQUAL "Intel")
           if (WIN32)
@@ -101,7 +103,9 @@ if (${F_COMPILER} STREQUAL "GFORTRAN" OR ${F_COMPILER} STREQUAL "F95" OR CMAKE_F
         endif ()
       endif ()
     else ()
-      set(FCOMMON_OPT "${FCOMMON_OPT} -m32")
+        if (NOT CMAKE_Fortran_COMPILER_ID MATCHES "LLVMFlang.*")
+           set(FCOMMON_OPT "${FCOMMON_OPT} -m32")
+	endif ()
     endif ()
   endif ()