use a proper cl_process parameter type
Remove unnecessary includes of buffer-private.h
Remove unnecessary includes of gegl-utils.h
Fix mixed declaration warnings
Remove more unnecessary includes
Remove obsolete types from types-internal.h
Enable GPL3 operations in gegl-tester
Don't use AvailabilityMacros on OSX (bug 673969)

These were inherited from the OSX system headers, but are meaningless
for GEGL because all functions are loaded dynamically.
linear_new_from_data: Fail if given an invalid rowstride

Previously this would result in a silently corrupted buffer.
Remove gimp specific code from gegl_buffer_add_handler