Prepare for using liblzma in wxWidgets code by adding the necessary
option and updating the configure check for it (which had been already
present due to libtiff possible dependency on liblzma).
No real changes yet.
Commit bc13119494 removed the inclusion of
xlocale.h because it is not (and never was) needed under Linux with
glibc, but it is still needed under macOS, so this (silently) disabled
wxXLocale support under Mac when using configure and broke the build
when using cmake.
Fix both problems by using xlocale.h only if it's available, both in
configure and in cmake.
Add CMake-based build system.
Merge the original branch without any changes except for resolving the
conflict due to moving the contents of .travis.yml to a separate file by
propagating the changes done in this file since then to the new script
and rerunning ./build/update-setup-h and ./build/cmake/update_files.py
to update the file lists changed in the meanwhile.
Closes https://github.com/wxWidgets/wxWidgets/pull/330
Add CMake build system for libraries, tests and samples
update_files.py converts build/files into CMake format.
build/update-setup-h has been modified to update build/cmake/setup.h.in.
