Fix profile feedback with -jN and add profile-fast

Fix profile feedback with -jN and add profile-fast

Profile feedback always failed for me with -jN. The problem
was that there was no implicit ordering between the profile generate
stage and the profile use stage. So some objects in the later stage
would be linked with profile generate objects, and fail due
to the missing -lgcov.

This adds a new profile target that implicitely enforces the
correct ordering by using submakes. Plus a profile-install target
to also install. This is also nicer to type that PROFILE=...

Plus I always run the performance test suite now for the full
profile run.

In addition I also added a profile-fast / profile-fast-install
target the only runs the performance test suite instead of the
whole test suite. This significantly speeds up the profile build,
which was totally dominated by test suite run time. However
it may have less coverage of course.

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>