Intel: Replace deprecated Fortran flag -nofor_main with -nofor-main

The `-nofor_main` flag was originally added by commit ccdd3e94 (Fix
Intel Fortran SHARED libraries on Linux, 2009-10-27, v2.8.2~915).  Since
then, Intel Fortran renamed the option to `-nofor-main` and deprecated
the old name.  The new name has been available for a long time, so
we can just switch to it.

Fixes: #21735

Modules/Platform/Linux-Intel-Fortran.cmake

 include(Platform/Linux-Intel)
 __linux_compiler_intel(Fortran)
-string(APPEND CMAKE_SHARED_LIBRARY_CREATE_Fortran_FLAGS " -nofor_main")
+string(APPEND CMAKE_SHARED_LIBRARY_CREATE_Fortran_FLAGS " -nofor-main")
 set(CMAKE_SHARED_LIBRARY_LINK_Fortran_FLAGS "")