Build libuafs with libtool

Use the standard program for building PIC and non-PIC object files,
instead of rolling our own.  This allows us to pull the build rules
into the Makefile.common, leaving just compiler flags and similar
in the MakefileProtos.

This does change the build flags being used to compile these files
somewhat -- the old CRULE1 and CRULEPIC used CC instead of CCOBJ
or MT_CC, and did not pass MT_CFLAGS, but it should be safe to
move to the standard compiler invocations.  We can also eliminate
the libuafs-specific 'OPTF' variable which expands to OPTMZ almost
everywhere.

Rename our COMMON_INCLUDE to MODULE_INCLUDE so it's picked up properly
by the standard build rules; this will let us remove
${TOP_OBJDIR}/src/config and ${TOP_INCDIR} once the rest of the
build rules in this Makefile are converted to use libtool, as those
include directories are already added by COMMON_INCL in Makefile.config.

As a side effect, we get rid of the LIBUAFS make variable -- all sites
were defining it to libuafs.a anyway, so we can just hardcode it.

We can also build a shared libuafs.la "for free".  Don't install
it anywhere just yet, though.

Change-Id: I2bda2f40bbd0aa808c24e074d2d7bcd329f6b77e
Reviewed-on: http://gerrit.openafs.org/11472
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: D Brashear <shadow@your-file-system.com>