Disable SSLv3 (POODLE attack) in GnuTLS: Bug #739019

This disables SSLv3 in GnuTLS (and therefore WebKit) to avoid
susceptibility to the POODLE attack vector.  This is an extremely
unlikely vector for Geary as Javascript is disabled for all WebKit
views.

configure

@@ -40,6 +40,8 @@ configure_help() {
 	                        Disable generating and installing translated help documentation.
 	  --disable-contractor
 	                        Disable installing Contractor files.
+	  --disable-poodle-ssl3
+	                        Disable POODLE SSLv3 GnuTLS priority fix. (Not recommended.)
 
 	Some influential environment variables:
 	  PKG_CONFIG_PATH       Adds directories to pkg-config's search path.
@@ -123,6 +125,10 @@ do
                             CMDLINE="${CMDLINE} -DDISABLE_CONTRACT=ON"
                             ;;
         
+        --disable-poodle-ssl3)
+                            CMDLINE="${CMDLINE} -DDISABLE_POODLE=ON"
+                            ;;
+        
         VALAC)              [ ! $value ] && abort $1
                             VALAC=$value
                             ;;