global: Use check-local in Makefile.am instead of overriding check directly This helps with dependency problems, like running "make check" in lib-storage without "make" first would try to compile the test programs too early and fail.

Moved fs-compress to a separate plugin directory. Mainly because I couldn't figure out how to make automake dependencies work on "make install" stage. It was trying to link fs-compress.so using -ldovecot-storage, but libdovecot-storage.so was also concurrently being installed.

lib-compression: Fixed dependency tracking in Makefile

Moved fs-compress from lib-fs to lib-compression. This solves build ordering issues.

lib-compression: Use libdovecot.so as dependency. Don't include liblib.a itself!

lib-compression: Added some unit testing for lib-compression. Not perfect in any way, but at least tests if things are completely broken.

Makefile: Added missing iostream-lz4.h

lib-compression: Added initial support for LZ4 There's no standard file format for LZ4, so we created our own. The code has had only minimal testing currently, so there may be bugs.

lib-compression: Added support for liblzma (xz) Annoyingly this is mainly copy&pasted [io]stream-bzlib, but I'm not sure if it's worth the effort to try to create common functions for them.

MODULE_LIBS is now part of LIBDOVECOT. No need to explicitly link it everywhere.

Makefile: Added missing headers

Moved zlib/bzlib code to lib-compression library.