Blender Git Loki

CMake patch from Alexander Neundorf

-under UNIX, it uses FIND_PACKAGE() to find the jpg, png and zlib libraries

-it removes the explictely listed search paths, which are already searched by
default, so it is not necessary to list them again explicitely

-it removes the include directories /usr/include
and /usr/local/include. /usr/include is used by default, all other
directories should be searched via find_package/find_file and then added to
the include directories.

-replaces the include() commands for the FindXXX.cmake
modules with the appropriate find_package(Foo) calls.
This doesn't change the behaviour, but gives more features.
E.g. you could now say
find_package(JPEG REQUIRED)
and cmake will abort with an error if the package is not found.
Also it makes it clearer what is going on.

Additionally the patch removes the line
INCLUDE(${CMAKE_ROOT}/Modules/Platform/Windows-cl.cmake)
in the Windows if-branch.
Why was this there ? This file should be included anyway under Windows when
using the MS compiler.