to catch library and header mismatch, also found at the end of pngtest.c.

as it was prior to libpng-1.2.16beta2, to simplify version differences.

so it will work with automake versions earlier than 1.11.1

to remove obsolete statement about a custom ltmain.sh

in printf statements in pngvalid.c, and changed %ud to %lu.

and re-removed mkinstalldirs.

that CCP writes to standard output by default (Martin Banky).

$AUTOHEADER, $AUTOPOINT, $ACLOCAL and $LIBTOOLIZE

Studio 2010 (John Bowler).

in pngpriv.h in case the user forgot to define them in their pngusr.h.  This
means it is safe for people not building a DLL to omit these defines from pngusr.h.

Also corrected zlib.vcxproj into which Visual Studio had introduced
what it calls an "authoring error".  The change to make pnglibconf.h
simply copies the file; in the future it may actually generate the
file from scripts/pnglibconf.dfa as the other build systems do.