Introduce inotify-based replacements for fs_mgr_wait_for_file.

Bug: 134966533
Test: fs_mgr_unit_test gtest
Change-Id: I36802b87cec59b5277267eb919851ca390fea425
diff --git a/fs_mgr/Android.bp b/fs_mgr/Android.bp
index ffde114..3d3503c 100644
--- a/fs_mgr/Android.bp
+++ b/fs_mgr/Android.bp
@@ -35,6 +35,7 @@
     export_include_dirs: ["include"],
     include_dirs: ["system/vold"],
     srcs: [
+        "file_wait.cpp",
         "fs_mgr.cpp",
         "fs_mgr_format.cpp",
         "fs_mgr_verity.cpp",