libs/posix: Implemented new locale functions

Implemented the missing POSIX functions in <locale.h>:
newlocale, duplocale, uselocale, and freelocale, and also
provided missing type definitions for <locale.h>.

Implemented missing POSIX locale-based function variants.

Modified LocaleBackend so that it could support thread-local
locales.

Some glibc-like locale-related variables supporting
ctype and printf family of functions have also been updated
to reflect the thread-local variables present in the latest
glibc sources.

As there have been some modifications to global symbols
in libroot, libroot_stubs.c has been regenerated.

Bug: #17168
Change-Id: Ibf296c58c47d42d1d1dfb2ce64042442f2679431
Reviewed-on: https://review.haiku-os.org/c/haiku/+/5351
Tested-by: Commit checker robot <no-reply+buildbot@haiku-os.org>
Reviewed-by: Adrien Destugues <pulkomandy@pulkomandy.tk>

strings.h: s/inline/__inline__/

As suggested by http://gcc.gnu.org/onlinedocs/gcc-4.2.4/gcc/Inline.html

This should fix building things like NBDkit.

Change-Id: I1da7fc140dd8451ff2ddaf599fe4e951401d0cb3
Reviewed-on: https://review.haiku-os.org/c/haiku/+/2794
Reviewed-by: Adrien Destugues <pulkomandy@gmail.com>

Optimize ffs() implementation

- Use gcc builtin
- Define as a static inline function in the .h so no function call overhead is needed
- Keep the function in libroot for backwards compatibility
- Remove a duplicate implementation in the freebsd compatibility layer

gcc2 does not document the builtin, but it is in fact already available
there as well.

Fixes #3281.

Change-Id: I94f8a2548637aa70e85febbfab06f07c1a427005
Reviewed-on: https://review.haiku-os.org/c/haiku/+/2605
Reviewed-by: waddlesplash <waddlesplash@gmail.com>

include strings.h where appriopriate...

instead or additionally to string.h, in preparation for functions move.
* moves str[n]casecmp() functions and others to strings.h.
* strings.h doesn't include string.h anymore.
* this solves #10949

Added our string.h headers (the one in private/kernel will be removed now)


git-svn-id: file:///srv/svn/repos/haiku/trunk/current@1070 a95241bf-73f2-0310-859d-f6bbb57e9c96

include strings.h where appriopriate...

instead or additionally to string.h, in preparation for functions move.
* moves str[n]casecmp() functions and others to strings.h.
* strings.h doesn't include string.h anymore.
* this solves #10949

Added our string.h headers (the one in private/kernel will be removed now)


git-svn-id: file:///srv/svn/repos/haiku/trunk/current@1070 a95241bf-73f2-0310-859d-f6bbb57e9c96