* c-format.h (format_kind_info): Add alloc_char field.
* c-format.c (scanf_flag_specs): Add 'm'.
(scanf_flag_pairs): Add 'a', 'm' pair.
(scan_char_table): Allow 'm' modifier for c, s, [, C and S.
(format_types_orig): Add alloc_char fields.
(check_format_info_main): Rename aflag to alloc_flag.
Handle fki->alloc_char. modifier after width and before length
modifiers. Move FMT_FLAG_SCANF_A_KLUDGE handling before
length modifiers as well.
* config/sol2-c.c (solaris_format_types): Add alloc_char field.
* gcc.dg/format/c90-scanf-5.c: New test.
* gcc.dg/format/c99-scanf-4.c: New test.
* gcc.dg/format/ext-7.c: New test.
* gcc.dg/format/ext-8.c: New test.