RFC: Renaming 'enum gfc_generic_isym_id'

[Daniel Franke]

Hi all,

in order to fix PR29651 et al., I want to distingiush between intrinsic 
subroutines. Currently all subroutines have isym->generic_id == GFC_ISYM_NONE 
which is not very helpful in this respect. 

To define a unique identifier for any intrinsics, I'd like to propose the 
following changes:

 (1) rename 'enum gfc_generic_isym_id' to 'enum gfc_isym_id'
 (2) add missing intrinsics to 'enum gfc_isym_id'
 (3) add an additional 'id' argument to 'add_sym_[012345][s]'
 (4) change all callers, add the corresponding 'gfc_isym_id'
 (5) rename member 'generic_id' in 'struct gfc_intrinsic_sym' to 'id'
 (6) change all callers

As especially (4) takes some time and effort I'd like to know whether there 
are any objections to this, maybe an implication I missed?!

Thanks
	Daniel