Define OSMAJOR as the OS major version, and add it to CFLAGS when
compiling libpkg sources.

Add new function: bool pkg_compiled_for_same_os_major(void) -- detect
when pkg(8) is running on a different OS major version than what it
was compiled for (presumably as a consequence of system upgrade)

Add INDEXDIR and INDEXFILE config file values to parallel the usage in
${PORTSDIR}/Makefile etc.  These are respectively the directory to
search for the ports index in (if undefined, defaults to the value of
PORTSDIR) and the filename of the index -- default INDEX-N where N is
the OS major version.
Fix typo.
Add some helpful advice for people doing major version upgrades.
Merge branch 'master' into indexfile
Autotoolizing
Fix a couple of evaluations
Build test program but do not allow to run them has atf/kyua has change
and are not yes usable as is
Check for atf-c.h to build regression tests
Test the right header
Add missing bits from autoconf
config.status should not be in
Force regenerating autoconf
Make the regression target a stub for now
aclocal.m4 got regenerated
regen again
Enforce std=gnu89 to fix build with gcc
Drop integrity check table after using.
Rework ordering and jobs solved.
Fix ordering in the packages universe.
Start to fix autoremove.