Disable mozjs extension by default

mozjs doesn't have a stable API, so distros wind up carrying a bunch of
patches to make it work with newer mozjs. Crashes ensue if it gets
linked into gjs applications and the versions don't match. There's
really no benefit to using this over the WebKit extension, so let's
nudge distros towards using that instead.

Distros: don't wait for this commit, go ahead and build with
-DWITH_MOZJS=OFF today to use the WebKit backend instead.

.travis.yml

@@ -39,6 +39,7 @@ script:
     -DWITH_GNOME3=ON  \
     -DWITH_KDE=ON     \
     -DWITH_WEBKIT3=ON \
+    -DWITH_MOZJS=ON   \
     -DBIPR=0
   - make
   - sudo make install

INSTALL

@@ -101,7 +101,7 @@ WITH_KDE:               Default to ON. Enables plug-in to read proxy settings
                         Note: this plug-in only has a *runtime* dependency on
                         either kreadconfig or kreadconfig5.
 
-WITH_MOZJS:             Default to ON. Enable Mozilla javascript bindings. As
+WITH_MOZJS:             Default to OFF. Enable Mozilla javascript bindings. As
                         Mozilla Javascript engine is often installed multiple
                         you can set prefered order using MOZJS_SEARCH_ORDER,
                         wich defaults to "xulrunner-js;firefox-js;mozilla-js;seamonkey-js".

libproxy/cmake/modules.cmk

@@ -44,7 +44,7 @@ if(NM_FOUND OR NMold_FOUND)
   set(NM_BUILD 1)
 endif(NM_FOUND OR NMold_FOUND)
 px_module(network_networkmanager   "${NM_BUILD}"     0       ${NM_LIBRARIES}${NMold_LIBRARIES})
-px_module(pacrunner_mozjs          "${MOZJS_FOUND}"  ${BIPR} ${MOZJS_LIBRARIES})
+px_module(pacrunner_mozjs          0                 ${BIPR} ${MOZJS_LIBRARIES})
 px_module(pacrunner_natus          "${NATUS_FOUND}"  ${BIPR} ${NATUS_LIBRARIES})
 px_module(pacrunner_webkit         "${WEBKIT_FOUND}" ${BIPR} ${WEBKIT_LIBRARIES})
 px_module(wpad_dns_alias           1                 1)