clang static analyzer is a source code analysis tool that
finds bugs in C, C++.

This patch automates clang analyzes part by integrating
it with 'make clang-check'

clang-checker.sh: runs clang analyzer with and without the
HEAD commit, and shows the bugs introduced by HEAD commit (if any)

sample report:

$[ glusterfs ]: make clang-check

================ Clang analyzer in progress ================
...

BASELINE BUGS LIST (before applying patch):
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Out of bound array access --> 3
Memory leak --> 1
Unix API --> 24
Dead increment --> 5
Dereference of null pointer --> 1995
Uninitialized argument value --> 2
All Bugs --> 2872
Called function pointer is null null dereference --> 4
Dead initialization --> 49
Dead assignment --> 691
Undefined allocation of 0 bytes CERT MEM0 C CWE --> 5
Argument with nonnull attribute passed null --> 84
Result of operation is garbage or undefined --> 9

TARGET BUGS LIST (after applying patch):
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Out of bound array access --> 3
Memory leak --> 1
Unix API --> 24
Dead increment --> 5
Dereference of null pointer --> 1995
Uninitialized argument value --> 2
All Bugs --> 2875
Called function pointer is null null
dereference --> 4
Dead initialization --> 49
Dead assignment --> 694
Undefined allocation of 0 bytes CERT MEM0 C CWE --> 5
Argument with nonnull attribute passed null --> 84
Result of operation is garbage or undefined --> 9

SUMMARY OF CLANG-ANALYZER:
~~~~~~~~~~~~~~~~~~~~~~~~~~
Extra 3 Bug[s] Introduced in: Dead assignment

Patch Value given by Clang analyzer '-1'

Explore complete results at
/home/user/work/glusterfs/baseline/results/index.html
/home/user/work/glusterfs/target/results/index.html

================= Done with Clang Analysis =================

Change-Id: I512e33cfc02885a111152fbc1832144261dda1da
BUG: 1228142
Signed-off-by: Prasanna Kumar Kalever <prasanna.kalever@redhat.com>
Reviewed-on: http://review.gluster.org/11083
Tested-by: Prasanna Kumar Kalever <pkalever@redhat.com>
NetBSD-regression: NetBSD Build System <jenkins@build.gluster.org>
CentOS-regression: Gluster Build System <jenkins@build.gluster.com>
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Smoke: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Raghavendra Talur <rtalur@redhat.com>
Reviewed-by: Kaleb KEITHLEY <kkeithle@redhat.com>