Manual removal of non-Linux source, documentation, etc.

Remove non-Linux source directories: freebsd/, svr4/, sunos4/, svr4/.
Remove README-freebsd, README-sunos4, README-svr4, m4/procfs.m4.

linux/sparc/{errnoent1,ioctlent1,signalent1}.h used to point to svr4/ files -
replace their contents with copies of used (and now deleted) files.
Make linux/sparc64/{errnoent1,ioctlent1,signalent1}.h include these files
instead of svr4/* ones.

Makefile.am: remove references to deleted files.
configure.ac: Remove a few tests which make no sense on Linux.
Man page: remove non-Linux quirks information.

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
37 files changed