re PR fortran/17776 (no subroutine system)

re PR fortran/17776 (no subroutine system)

fortran/
PR fortran/17776
* check.c (gfc_check_system_sub): New function.
* gfortran.h (gfc_generic_isym_id): Add GFC_ISYM_SYSTEM.
* intrinsic.c (add_functions): Add 'system'.
(add_subroutines): Add 'system'.
* intrinsic.h (gfc_check_etime_sub, gfc_check_getcwd_sub):
Move prototypes to other suborutines.
(gfc_check_system_sub, gfc_resolve_system, gfc_resolve_system_sub):
Add prototype.
(gfc_resolve_system_clock): Fix formatting of prototype.
* iresolve.c (gfc_resolve_system, gfc_resolve_system_sub): New
functions.
* trans-intrinsic.c (gfc_conv_intrinsic_function): Deal with
GFC_ISYM_SYSTEM.

libgfortran/
PR fortran/17776
* intrinsics/system.c: New file.
* Makefile.am: Add dependency for the new file.
* Makefile.in: Regenerate.

From-SVN: r88532