Fix installd to create /data/data/<pkgname> with appropriate permissions.

The directory was created with read+exec rights for others.
The patch restricts it to only exec rights.
diff --git a/cmds/installd/commands.c b/cmds/installd/commands.c
index 1e8555b..cd0302c 100644
--- a/cmds/installd/commands.c
+++ b/cmds/installd/commands.c
@@ -39,7 +39,7 @@
             return -1;
     }
 
-    if (mkdir(pkgdir, 0755) < 0) {
+    if (mkdir(pkgdir, 0751) < 0) {
         LOGE("cannot create dir '%s': %s\n", pkgdir, strerror(errno));
         return -errno;
     }