re PR fortran/13702 (When preprocessing Fortran files (.F, .F90 and .F95) cpp should emit line numbers.)

PR fortran/13702
(Port from g95)
* gfortran.h (gfc_linebuf): New typedef.
(linebuf): Remove.
(gfc_file): Revamped, use new gfc_linebuf.
(locus): Revamped, use new types.
(gfc_current_file): Remove.
(gfc_current_form, gfc_source_file): New global variables.
* match.c (gfc_match_space, gfc_match_strings): Use
gfc_current_form to find source form.
* module.c (gfc_dump_module): Use gfc_source_file when printing
module header.
* error.c (show_locus, show_loci) Use new data structures to print
locus.
* scanner.c (first_file, first_duplicated_file, gfc_current_file):
Remove.
(file_head, current_file, gfc_current_form, line_head, line_tail,
gfc_current_locus1, gfc_source_file): New global variables.
(gfc_scanner_init1): Set new global variables.
(gfc_scanner_done1): Free new data structures.
(gfc_current_locus): Return pointer to gfc_current_locus1.
(gfc_set_locus): Set gfc_current_locus1.
(gfc_at_eof): Set new variables.
(gfc_at_bol, gfc_at_eol, gfc_advance_line, gfc_next_char): Adapt
to new locus structure.
(gfc_check_include): Remove.
(skip_free_comments, skip_fixed_comments): Use gfc_current_locus1.
(gfc_skip_comments): Use gfc_current_form, find locus with
gfc_current_locus1.
(gfc_next_char): Use gfc_current_form.
(gfc_peek_char, gfc_gobble_whitespace): Use gfc_current_locus1.
(load_line): Use gfc_current_form. Recognize ^Z as EOF. Fix
comment formatting.
(get_file): New function.
(preprocessor_line, include_line): New functions.
(load_file): Move down, rewrite to match new data structures.
(gfc_new_file): Rewrite to match new data structures.
* parse.c (next_statement): Remove code which is now useless. Use
gfc_source_form and gfc_source_file where appropriate.
* trans-decl.c (gfc_get_label_decl): adapt to new data structures
when determining locus of frontend code.
* trans-io.c (set_error_locus): Same.
* trans.c (gfc_get_backend_locus, gfc_set_backend_locus): Likewise.
* lang-specs.h (@f77-cpp-input, @f95-cpp-input): Remove '-P' from
preprocessor flags.
(all): Add missing initializers.

From-SVN: r81888