Fix path to sysroots for git

Test: update_prebuilts.sh 8215242
Change-Id: I8f9ccfa0742175209778df8cd5a5741c638f6c5f
diff --git a/update-prebuilts.sh b/update-prebuilts.sh
index 0ac14c2..d414a3f 100755
--- a/update-prebuilts.sh
+++ b/update-prebuilts.sh
@@ -62,7 +62,7 @@
 
 cp -f "${tmpdir}/manifest.xml" manifest.xml
 
-git add manifest.xml linux-x86 darwin-x86 common x86_64-linux-musl i686-linux-musl
+git add manifest.xml linux-x86 darwin-x86 common sysroots/x86_64-linux-musl sysroots/i686-linux-musl
 git commit -m "Update build-tools to ab/${BUILD_NUMBER}
 
 https://ci.android.com/builds/branches/aosp-build-tools-release/grid?head=${BUILD_NUMBER}&tail=${BUILD_NUMBER}