configure: add --disable-zlib-test

This is required for building libcacard which doesn't itself require
zlib without bringing in this requirement to the build environment.

Signed-off-by: Alon Levy <alevy@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

configure

@@ -179,6 +179,7 @@ smartcard=""
 smartcard_nss=""
 usb_redir=""
 opengl=""
+zlib="yes"
 
 # parse CC options first
 for opt do
@@ -751,6 +752,8 @@ for opt do
   ;;
   --enable-usb-redir) usb_redir="yes"
   ;;
+  --disable-zlib-test) zlib="no"
+  ;;
   *) echo "ERROR: unknown option $opt"; show_help="yes"
   ;;
   esac
@@ -1190,6 +1193,7 @@ fi
 ##########################################
 # zlib check
 
+if test "$zlib" != "no" ; then
     cat > $TMPC << EOF
 #include <zlib.h>
 int main(void) { zlibVersion(); return 0; }
@@ -1203,6 +1207,7 @@ else
         echo
         exit 1
     fi
+fi
 
 ##########################################
 # xen probe