Add zlib to configure script

configure.ac

@@ -48,6 +48,7 @@ if test "x$ax_cv_ncursesw" != xyes && test "x$ax_cv_ncurses" != xyes; then
   AC_MSG_ERROR([requires either NcursesW or Ncurses library])
 fi
 
+PKG_CHECK_MODULES([ZLIB], [zlib])
 PKG_CHECK_MODULES([LIBCURL], [libcurl],, [LIBCURL_CHECK_CONFIG])
 PKG_CHECK_MODULES([CPPUNIT], [cppunit],, [no_cppunit="yes"])
 PKG_CHECK_MODULES([DEPENDENCIES], [libtorrent >= 0.15.1])
@@ -77,9 +78,9 @@ CC_ATTRIBUTE_UNUSED(
 
 dnl Only update global build variables immediately before generating the output,
 dnl to avoid affecting the global build environment for other autoconf checks.
-LIBS="$PTHREAD_LIBS $CURSES_LIB $CURSES_LIBS $LIBCURL $LIBCURL_LIBS $DEPENDENCIES_LIBS $LIBS"
-CFLAGS="$CFLAGS $PTHREAD_CFLAGS $LIBCURL_CPPFLAGS $LIBCURL_CFLAGS $DEPENDENCIES_CFLAGS $CURSES_CFLAGS"
-CXXFLAGS="$CXXFLAGS $PTHREAD_CFLAGS $LIBCURL_CPPFLAGS $LIBCURL_CFLAGS $DEPENDENCIES_CFLAGS $CURSES_CFLAGS"
+LIBS="$PTHREAD_LIBS $ZLIB_CFLAGS $CURSES_LIB $CURSES_LIBS $LIBCURL $LIBCURL_LIBS $DEPENDENCIES_LIBS $LIBS"
+CFLAGS="$CFLAGS $PTHREAD_CFLAGS $ZLIB_CFLAGS $LIBCURL_CPPFLAGS $LIBCURL_CFLAGS $DEPENDENCIES_CFLAGS $CURSES_CFLAGS"
+CXXFLAGS="$CXXFLAGS $PTHREAD_CFLAGS $ZLIB_LIBS $LIBCURL_CPPFLAGS $LIBCURL_CFLAGS $DEPENDENCIES_CFLAGS $CURSES_CFLAGS"
 
 AC_CONFIG_FILES([
   Makefile