Support coverage testing with GCC/gcov

I noticed two small things that I'd like to fix before this goes 'next', so here they are:

* [1/8] Support coverage testing with GCC/gcov

Changed it so the compilation (but not the testing) uses the same -j flags as the caller, so that compilation can be done in parallel. (It's rather minor compared to the slow testing with optimizations turned off, but still.)

* [5/8] Test fsck a bit harder

Fixed an invocation of hash-objects that lacked --stdin. I also added some debugging cats to make it easier to fix the grep invocation when fsck actually starts printing errors for these corruptions.

Apart from that it's the same.

Thanks!

Thomas Rast (8):
Support coverage testing with GCC/gcov
Test that diff can read from stdin
Test diff --dirstat functionality
Test log --graph
Test fsck a bit harder
Test log --decorate
Test rev-list --parents/--children
Test git-patch-id

 Makefile                                      |   24 ++++
 t/t1450-fsck.sh                               |   67 +++++++++++
 t/t4002-diff-basic.sh                         |    8 ++
 t/t4013-diff-various.sh                       |    5 +
 t/t4013/diff.diff_--dirstat_master~1_master~2 |    3 +
 t/t4013/diff.log_--decorate_--all             |   34 ++++++
 t/t4013/diff.rev-list_--children_HEAD         |    7 +
 t/t4013/diff.rev-list_--parents_HEAD          |    7 +
 t/t4202-log.sh                                |  148 +++++++++++++++++++++++++
 t/t4203-patch-id.sh                           |   38 +++++++
 10 files changed, 341 insertions(+), 0 deletions(-)
 create mode 100644 t/t4013/diff.diff_--dirstat_master~1_master~2
 create mode 100644 t/t4013/diff.log_--decorate_--all
 create mode 100644 t/t4013/diff.rev-list_--children_HEAD
 create mode 100644 t/t4013/diff.rev-list_--parents_HEAD
 create mode 100755 t/t4203-patch-id.sh