Teach the Dwarf 2 reader to read macro information.

Teach the Dwarf 2 reader to read macro information.
* dwarf2read.c: #include "macrotab.h".
(dwarf_macinfo_buffer): New variable.
(struct dwarf2_pinfo): New members: dwarf_macinfo_buffer, and
dwarf_macinfo_size.
(DWARF_MACINFO_BUFFER, DWARF_MACINFO_SIZE): New macros.
(dwarf2_missing_macinfo_section, dwarf2_macros_too_long,
dwarf2_macros_not_terminated, dwarf2_macro_outside_file,
dwarf2_macro_unmatched_end_file, dwarf2_macro_malformed_definition,
dwarf2_macro_spaces_in_definition): New complaints.
(dwarf2_has_info): Initialize dwarf_macinfo_offset.
(dwarf2_build_psymtabs): Read the .dwarf_macinfo section.
(dwarf2_build_psymtabs_hard): Record the buffer and its size in
the partial symbol table.
(psymtab_to_symtab_1): Set the macinfo buffer and size globals
from what's recorded in the partial symbol table.
(read_file_scope): If the compilation unit has a
`DW_AT_macro_info' attribute, read its macro information.
* Makefile.in (dwarf2read.o): Depend on macrotab.h.