Add unittests for file_scanner. Fix minor bug.

Bug: 73625480
Change-Id: Ice90c62ee6dd9742add9627cf7d8c9b9f2e6d741
diff --git a/tools/test_data.txt b/tools/test_data.txt
index c0692b0..36c9cdb 100644
--- a/tools/test_data.txt
+++ b/tools/test_data.txt
@@ -1,3 +1,4 @@
 # List of test deps that should be pushed on the device. Paths are relative
 # to the root.
 src/ftrace_reader/test/data/
+src/traced/probes/filesystem/testdata/