build system: Further improve quiet mode (Jan Kiszka)

build system: Further improve quiet mode (Jan Kiszka)

Derived from Stuart Brady's patch: Show the target directory as prefix
to the current module when building in quiet mode. This helps to gain
overview of the current build progress, specifically when running
parallelized builds.

Furthermore, suppress make command echoing when entering subdirs and
replace $(subst subdir-,,$@) with $* in the related rule.

Signed-off-by: Jan Kiszka <[email protected]>
Signed-off-by: Anthony Liguori <[email protected]>
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@6447 c046a42c-6fe2-441c-8c8c-71466251a162