Add sparse checker support to the build system (Gerd Hoffman)

Add sparse checker support to the build system (Gerd Hoffman)

This adds support for running the sparse checker during the build
process.  Left it off by default for now, build becomes very noisy with
sparse checking turned on as it has to complain alot (partly even in the
system headers!).  The qemu code base needs quite some cleanups before
we should consider turning it on by default.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5440 c046a42c-6fe2-441c-8c8c-71466251a162