AC_CHECK_LIB(z, zlibVersion,, AC_ERROR([ZLib not installed]))
AC_ARG_WITH(pkgconfigdir, AC_HELP_STRING([--with-pkgconfigdir],[Use the specified pkgconfig dir (default is prefix/lib/pkgconfig)]),[PKGCONFIGDIR=${withval}],[PKGCONFIGDIR='${prefix}/lib/pkgconfig'])