Hi Philip, glad to hear it worked ok.
Yes, I saw the same message. It might look like something went wrong but in fact (at least by my reading of that referenced MakeDepend.pm file at line 104) it is just a warning. It is checking syntax of PNG/libpng/pngconf.h and gets confused by this line
#if (PNG_ZBUF_SIZE > 65536L) && defined(PNG_MAX_MALLOC_64K)
but it is harmless.
(And I *think* is not related to my fixes although you never know).