prebuilts: don't try to relink again if source is unavailable
diff --git a/prebuilt/relink.sh b/prebuilt/relink.sh
index 3fa627f..4b29a7e 100755
--- a/prebuilt/relink.sh
+++ b/prebuilt/relink.sh
@@ -1,9 +1,14 @@
-#!/bin/bash -x
+#!/bin/bash
 
 process_file()
 {
     dst=$1/$(basename $2)
     src=$2
+
+    if [ ! -e $src ]; then
+      return
+    fi
+
     if [ $dst == $src ]; then
       cp -f -p $src $src.tmp
       src=$2.tmp