* fortran/intrinsic.c (add_functions): Change gfc_check_btest,
gfc_check_ibclr, and gfc_check_ibset to gfc_check_bitfcn.
* fortran/intrinsic.h: Remove prototypes for gfc_check_btest,
gfc_check_ibclr, and gfc_check_ibset. Add prototype for
gfc_check_bitfcn.
* fortran/check.c (nonnegative_check, less_than_bitsize1,
less_than_bitsize2): New functions.
(gfc_check_btest): Renamed to gfc_check_bitfcn. Use
nonnegative_check and less_than_bitsize1.
(gfc_check_ibclr, gfc_check_ibset): Removed.
(gfc_check_ibits,gfc_check_mvbits): Use nonnegative_check and
less_than_bitsize1.