GC4 issues to fix

[ddeclerck]

This lists issues that came up when merging GC3 patches to GC4.

• 1. Decide what to do about gcdiff, espacially under MSVC (see here for details)
• 2. Correctly implement delay-loading under MSVC
• 3. Possibly drop usage of external cobxref (see here for details)
• 4. Fix any remaining failed test case (especially MSVC ones)
• 5. Rework the context-sensitive reserved words handling (or use a bigger type)
• 6. Investigate the two CHECKMEs about bdb_close_cursor in fbdb.c:ix_bdb_write_internal
• 7. Investigate the CHECKMEs in typeck.c:validate_move and in particular why it was necessary to add CB_LITERAL_P (checks to add in parser)
• 8. Investigate CHECKME about the need for comma in move.c:cob_move_display_to_edited (first in GC 3.x)
• 9. Investigate the CHECKME about moving cob_set_exception call in common.c:cob_module_global_enter
• 10. Investigate the TODO about cb_default_byte in codegen.c:output_initialize
• 11. Make status an enum instead of an int in fileio.c:cob_file_save_status
• 12. Move the IO status codes from common.h to fileio.h as per TODO
• 13. Make field type an enum instead of a short in common.h:cob_field_attr as per TODO
• 14. Investigate INITIALIZE BY VALUE (currently under #if 0) in field.c:validate_field_value
• 15. Check the code for setting last_exception_source (currently under #if 0) in common.c:cob_set_exception
• 16. Deal with the TODO about EOP exception in fileio.c:cob_file_save_status
• 17. Investigate the need to define READ_WRITE_NEEDS_FLUSH under MacOS ("LINE SEQUENTIAL COMMIT / ROLLBACK" test fails if not defined)
• 18. Check if should use strcpy or memcpy with computed max-length for file_open_name in fileio.c:cob_open
• 19. Check what we should do about the casts used to remove const on open_mode in fileio.c and others (eg. in cob_open_file)