patch to use system's zlib when enabled by the CMake option USE_SYSTEM_ZLIB
Fix include-paths for timidity (Issue 180)
patch to use system's libpng when enabled by the CMake option USE_SYSTEM_LIBPNG
Use system's libjpeg when -DUSE_SYSTEM_LIBJPEG is used

note, that it is expected that this libjpeg is newer, therefore some files needs to be patched
to compile.

This patch is used for Debian -- Debian uses libjpeg-turbo, but I assume that it will also compile
against a recent libjpeg.
Merge pull request #192 from coldtobi/fix_183_libjpeg

Fix 183 libjpeg