git: Make submodule check only needed modules

If one is compiling more than one tree from the same source, it is
possible that they need different submodules.  Change the check to see
that all modules that we are interested in are updated, discarding the
ones that we don't care about.

Signed-off-by: Juan Quintela <quintela@redhat.com>

---

v1->v2:
patchw insists in not using modules

scripts/git-submodule.sh

@@ -59,10 +59,14 @@ status)
     fi
 
     test -f "$substat" || exit 1
-    CURSTATUS=$($GIT submodule status $modules)
-    OLDSTATUS=$(cat $substat)
-    test "$CURSTATUS" = "$OLDSTATUS"
-    exit $?
+    for module in $modules; do
+        CURSTATUS=$($GIT submodule status $module)
+        OLDSTATUS=$(cat $substat | grep $module)
+        if test "$CURSTATUS" != "$OLDSTATUS"; then
+            exit 1
+        fi
+    done
+    exit 0
     ;;
 update)
     if test -z "$maybe_modules"