new modules c32tolower, c32toupper

[Bruno Haible]

The function mbrtoc32 transforms a multibyte character to a char32_t,
thus solving the "wchar_t mess", explained in
https://www.gnu.org/software/libunistring/manual/html_node/The-wchar_005ft-mess.html
 .

But while ISO C 11..23 has upper/lowercase mapping functions for wchar_t
(towlower, towupper), is does not have such functions for char32_t values.

With these patches, I'm adding towlower / towupper workalike functions
for char32_t.


2023-04-09  Bruno Haible  <bruno@clisp.org>

        c32toupper: Add tests.
        * tests/test-c32toupper.sh: New file.
        * tests/test-c32toupper.c: New file, based on tests/test-c32islower.c.
        * modules/c32toupper-tests: New file.

        c32toupper: New module.
        * lib/uchar.in.h (c32toupper): New declaration.
        * lib/c32toupper.c: New file.
        * modules/c32toupper: New file.
        * m4/uchar_h.m4 (gl_UCHAR_H_REQUIRE_DEFAULTS): Initialize
        GNULIB_C32TOUPPER.
        * modules/uchar (Makefile.am): Substitute GNULIB_C32TOUPPER.

2023-04-09  Bruno Haible  <bruno@clisp.org>

        c32tolower: Add tests.
        * tests/test-c32tolower.sh: New file.
        * tests/test-c32tolower.c: New file, based on tests/test-c32isupper.c.
        * modules/c32tolower-tests: New file.

        c32tolower: New module.
        * lib/uchar.in.h (c32tolower): New declaration.
        * lib/c32tolower.c: New file.
        * lib/c32to-impl.h: New file, based on lib/c32is-impl.h.
        * modules/c32tolower: New file.
        * m4/uchar_h.m4 (gl_UCHAR_H_REQUIRE_DEFAULTS): Initialize
        GNULIB_C32TOLOWER.
        * modules/uchar (Makefile.am): Substitute GNULIB_C32TOLOWER.

0001-c32tolower-New-module.patch
Description: Text Data

0002-c32tolower-Add-tests.patch
Description: Text Data

0003-c32toupper-New-module.patch
Description: Text Data

0004-c32toupper-Add-tests.patch
Description: Text Data