iOS framework build script changes

- buildbot process support (break build in case of errors)
- disabled some warnings in cmake script
Fixed iOS framework compilation warnings
iOS framework build script changes from master branch
superres: Fix return value VideoFrameSource_GPU

superres module fails to compile with the following error messages:

[100%] Building CXX object modules/superres/CMakeFiles/opencv_superres.dir/src/super_resolution.cpp.o
/opencv-2.4.10/modules/superres/src/frame_source.cpp: In function 'cv::Ptr<cv::superres::FrameSource> cv::superres::createFrameSource_Video_GPU(const string&)':
/opencv-2.4.10/modules/superres/src/frame_source.cpp:263:16: error: expected type-specifier before 'VideoFrameSource'
/opencv-2.4.10/modules/superres/src/frame_source.cpp:263:16: error: could not convert '(int*)operator new(4ul)' from 'int*' to 'cv::Ptr<cv::superres::FrameSource>'
/opencv-2.4.10/modules/superres/src/frame_source.cpp:263:16: error: expected ';' before 'VideoFrameSource'
/opencv-2.4.10/modules/superres/src/frame_source.cpp:263:41: error: 'VideoFrameSource' was not declared in this scope
/opencv-2.4.10/modules/superres/src/frame_source.cpp:264:1: error: control reaches end of non-void function [-Werror=return-type]
cc1plus: some warnings being treated as errors
make[3]: *** [modules/superres/CMakeFiles/opencv_superres.dir/src/frame_source.cpp.o] Error 1
make[3]: *** Waiting for unfinished jobs....

This is caused because the return value of the createFrameSource_Video_GPU function should be a VideoFrameSource_GPU object.
fixing cap_pvpapi interface and making sure both AVT Manta and Proscilla
series are supported. Testing this with both cams for Windows and Linux
exhaustively.

Optimizing memory footprint by removing unused calls.

Adapted with the input of Shai

Added small example that illustrates how it should work.
cmake/OpenCVGenPkgconfig.cmake: rework opencv.pc generation

Using absolute path to locate the components in the "Libs:" field of the
*.pc can badly break cross-compilation, especially when building
statically linked objects.

Indeed, pkg-config automatically replaces the '-I...' and '-L...' paths
when the PKG_CONFIG_SYSROOT_DIR and PKG_CONFIG_LIBDIR environment
variables are set [1]. This feature is very helpful and common in
cross-compilation framework like Buildroot [2,3].

When there are absolute paths in the *.pc files, pkg-config won't be
able to do the path substitions for these paths when the afromentioned
environment variables are set.
In such case, since the prefix is the target one, not the sysroot one,
these libraries' abolute paths will point to:
- in the best case: a non-existing file (i.e. these files do not exists
  on the host system;
- at worst: the host system's libraries. This will make the linking
  failed because these host system's libraries will most likely not be
  build for the target architecture [4].

So, this patch replace the components' absolute paths by the form:
  -L<libdir> -l<libname>

This way, the linker will be able to resolve each dependency path,
whatever the kind of objects/build (shared object or static build) it
is dealing with.

Note that for static link, the library order does matter [5]. The order
of the opencv components has been carefully chosen to comply with this
requirement.

Fixes #3931

[1] http://linux.die.net/man/1/pkg-config
[2] http://buildroot.org/
[3] http://git.buildroot.net/buildroot/tree/package/pkgconf/pkg-config.in
[4] http://autobuild.buildroot.net/results/e8a/e8a859276db34aff87ef181b0cce98916b0afc90/build-end.log
[5] http://stackoverflow.com/questions/45135/linker-order-gcc

Signed-off-by: Samuel Martin <s.martin49@gmail.com>

---
Note: this patch properly applies on top of the master branch, though it
      has been written on top of the 2.4 branch.
Merge pull request #3376 from vriera:2.4
Merge pull request #3294 from mshabunin:fix-ios-warnings-24
Merge pull request #3305 from tSed:opencv-2.4.x/opencv.pc-generation-refactoring
Merge pull request #3322 from StevenPuttemans:fix_pvpapi_interface
Suppress a bogus -Warray-bounds in modules/superres/src/optical_flow.cpp

This is actually the same warning that the suppression at the bottom
suppresses, but that one doesn't suppress it when using a native compiler
(go figure).

I remove the forced inclusion of precompiled headers into all sources,
since otherwise this workaround doesn't work - the header with the warning
is included before I can use a pragma.
Merge pull request #3401 from SpecLad:optflow-bogus-Warray-bounds
adding extra buffer parameter
Fix uninitialized memory reads and memory leaks in StereoGC
ocl: Fix crash during destruction of gauss_w_lut object in hog.cpp

gauss_w_lut is a statically defined variable of type oclMat.  The oclMat
destructor calls openCLFree() which via getInitializationMutex() accesses
the __module variable which has been statically defined in cl_context.cpp

Since the destruction order of statically defined variables in different
compilation units is undefined, it is possible that __module will
be destructed before gauss_w_lut, which would result in a segfault when
getInitializationMutex() is called while destructing gauss_w_lut.

In order to avoid this issue, we need to make gauss_w_lut a private
member of the HOGDescriptors class so we know it will be destroyed
before __module.
attemp to fix dox warning
Merge pull request #3417 from ilya-lavrenov:dox_warn
C++ sample code to detect facial features
Merge pull request #3418 from tstellarAMD:2.4-hog-crash-fix
Merge pull request #3414 from SpecLad:vg-stereogc