Back port of include change and copyright from 5.1
Makefile.am, zlib.m4:
  Use separate libtool convenience library for the bundled
  zlib to embed into executables and shared libraries created,
  and one to install into the pkglib directory


zlib/Makefile.am:
  Use separate libtool convenience library for the bundled
  zlib to embed into executables and shared libraries created,
  and one to install into the pkglib directory
config/ac-macros/zlib.m4:
  Use separate libtool convenience library for the bundled
  zlib to embed into executables and shared libraries created,
  and one to install into the pkglib directory
mysys/my_memmem.c:
  Back port of include change and copyright from 5.1