[build] Add py_srcs.gni

Mako is imported by a few mesa build actions. Those actions can add
these srcs to their inputs to improve hermeticity.

Change-Id: Ie268a0cdb2039a900eeb3c9b555b94bdcd1997c2
Reviewed-on: https://fuchsia-review.googlesource.com/c/third_party/mako/+/503619
Reviewed-by: Anirudh Mathukumilli <rudymathu@google.com>
Reviewed-by: David Fang <fangism@google.com>
diff --git a/README.fuchsia b/README.fuchsia
index bb0279e..ccf53ee 100644
--- a/README.fuchsia
+++ b/README.fuchsia
@@ -9,3 +9,6 @@
 non-XML syntax which compiles into Python modules for maximum
 performance.
 
+Local Modifications:
+Added README.fuchsia.
+Added py_srcs.gni.
diff --git a/py_srcs.gni b/py_srcs.gni
new file mode 100644
index 0000000..3b620ca
--- /dev/null
+++ b/py_srcs.gni
@@ -0,0 +1,31 @@
+# Scripts import mako from third_party should have these sources added to their
+# `inputs` variable of their corresponding actions. This makes changes in this
+# library correctly trigger rebuilds of those actions in incremental builds.
+third_party_mako_srcs = [
+  "//third_party/mako/mako/__init__.py",
+  "//third_party/mako/mako/_ast_util.py",
+  "//third_party/mako/mako/ast.py",
+  "//third_party/mako/mako/cache.py",
+  "//third_party/mako/mako/cmd.py",
+  "//third_party/mako/mako/codegen.py",
+  "//third_party/mako/mako/compat.py",
+  "//third_party/mako/mako/exceptions.py",
+  "//third_party/mako/mako/ext/__init__.py",
+  "//third_party/mako/mako/ext/autohandler.py",
+  "//third_party/mako/mako/ext/babelplugin.py",
+  "//third_party/mako/mako/ext/beaker_cache.py",
+  "//third_party/mako/mako/ext/extract.py",
+  "//third_party/mako/mako/ext/linguaplugin.py",
+  "//third_party/mako/mako/ext/preprocessors.py",
+  "//third_party/mako/mako/ext/pygmentplugin.py",
+  "//third_party/mako/mako/ext/turbogears.py",
+  "//third_party/mako/mako/filters.py",
+  "//third_party/mako/mako/lexer.py",
+  "//third_party/mako/mako/lookup.py",
+  "//third_party/mako/mako/parsetree.py",
+  "//third_party/mako/mako/pygen.py",
+  "//third_party/mako/mako/pyparser.py",
+  "//third_party/mako/mako/runtime.py",
+  "//third_party/mako/mako/template.py",
+  "//third_party/mako/mako/util.py",
+]