This is subdirectory src/liblzma of xz-utils-4.999.9beta, except for files
Makefile.in, Makefile.win and R_changes

common/{bswap,integer,mythread}.h are from xz-utils-4.999.9beta.

check/{sha256.c,crc_macros.h} is modified to look on the usual include path.

common/local.h is a set of definitions of features to be built, and
common/sysdef.h is a modified copy of
xz-utils-4.999.9beta/common/sysdefs.h which includes it.

All the files from xz-utils are in the public domain.

The subblock encoder is not used: it is not configured in by
default and seems not to work on x86_64 platforms.

Performance optimizations are only used on Windows: it is assumed that on
other systems an optimized system liblzma is or could be made available.
