Add "pretty" build option

Add "pretty" build option

Add the capability to do a "pretty" build, where we output something
like "  CC  /path/to/foo.o" to build foo.o, instead of the entire
compiler invocation, similarly to how the Linux kernel build appears.
Add the "pretty" building for CC and LD rules.

This also prints out some helpful information when a command fails,
which can sometimes otherwise be annoying to figure out post-mortem.

To enable the pretty building, make with V=0. To output everything
that is actually run with V=0, make with 'V=0 Q=' .

Note that this does not work with all makes, since not all makes will
propagate command-line-specified variables to sub-makes without -e.
Non-working makes include /usr/ccs/bin/make on HP-UX and Solaris.
However, GNU make will work, as will /usr/xpg4/bin/make on Solaris.

Change-Id: Idce0afffe7d5be88b0743ec3f926a52efb1a6a74
Reviewed-on: http://gerrit.openafs.org/4486
Reviewed-by: Russ Allbery <rra@stanford.edu>
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementix.org>