Make the CMake build more pkg-config friendly

Build & install a libarchive.pc file, like autotools
Move .pc generation to a dedicated script (#55).
Merge branch 'master' into cmake-pkgconfig
Merge branch 'master' into cmake-pkgconfig
Merge remote-tracking branch 'upstream/master' into cmake-pkgconfig
Add --ignore-zeros option to bsdtar

This option is an alias for --options read_concatenated_archive
introduced for compatibility with GNU tar.

Signed-off-by: Kevin Locke <kevin@kevinlocke.name>
Merge remote-tracking branch 'upstream/master' into cmake-pkgconfig
Fix a couple of minor warnings.

Just so that the build passes w/ -Werror
Do not redefine _WIN32_WINNT and WINVER
Merge pull request #64 from NiLuJe/fix-warning

Fix a couple of minor warnings.
Merge remote-tracking branch 'upstream/master' into cmake-pkgconfig
Zip: Make Mac extension handling optional with "mac-ext" option for Zip, default true on Mac OS"
Fix: process directory entries even when mac extensions are turned off
Enable mac extensions for mac extension test
streaming zip reader does not support mac extensions
Return correct error when multiple modules match an option spec
mtree: Make reading additional information from the fs optional

This feature is not needed if users just want to read in the content of
an mtree file and do validation against the file system themselves.

It is needed for `bsdtar cvf out.tar @input.mtree` which is why the
option is enabled in bsdtar.

Since the mtree tests rely on this feature, this patch also enables it
there.

Signed-off-by: Florian Pritz <bluewind@xinu.at>
Merge pull request #65 from Bluewind/working

mtree: Make reading additional information from the fs optional
fixes to build by Open Watcom toolchain
rest of changes to be buildable by Open Watcom