Integrate lcov/gcov into Libav

The gcov/lcov are a common toolchain for visualizing code coverage with
the GNU/Toolchain. The documentation and implementation of this
integration was heavily inspired from the blog entry by Mike Melanson:
http://multimedia.cx/eggs/using-lcov-with-ffmpeg/
x86: sbrdsp: Implement SSE neg_odd_64

Timing on Arrandale:
        C   SSE
Win32:  57   44
Win64:  47   38
Unrolling and not storing mask both save some cycles.

Signed-off-by: Diego Biurrun <diego@biurrun.de>
fate: add coverage for background disposal in gif decoder

Signed-off-by: Paul B Mahol <onemda@gmail.com>
Merge commit 'a862c7d3368241e72a465ab944afa38ea62a6640'

* commit 'a862c7d3368241e72a465ab944afa38ea62a6640':
  Integrate lcov/gcov into Libav

Conflicts:
	Makefile
	common.mak

Merged-by: Michael Niedermayer <michaelni@gmx.at>
Merge remote-tracking branch 'qatar/master'

* qatar/master:
  x86: sbrdsp: Implement SSE neg_odd_64

Conflicts:
	libavcodec/x86/sbrdsp.asm

Merged-by: Michael Niedermayer <michaelni@gmx.at>
coverage: filter /usr/include out

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>