[libpng17] Made transform implementation functions static. This makes the

internal functions called by png_do_{read|write}_transformations static.
On an x86-64 DLL build (Gentoo Linux) this reduces the size of the text
segment of the DLL by 1208 bytes, about 0.6%. It also simplifies
maintenance by removing the declarations from pngpriv.h and allowing
easier changes to the internal interfaces.
5 files changed