Always emit original sources from scan_sources.

scan_sources.py should always emit the original source files passed as input,
even if it cannot find them. This is necessary to create a proper dependency
arc from the build rule "mojo_nacl" to the generated source "libmojo.cc" from
the "monacl_codegen" build rule..

It's not sufficient to convey this source dependency through ninja depfiles.
This is because the emitted dependency in the mojo_nacl.ninja from "mojo_nacl"
to "monacl_codegen" is order-only and depenencies are scanned before order-only
dependencies are run (ninja-build/ninja#760).

BUG=https://code.google.com/p/chromium/issues/detail?id=440451
TEST=manually modified libmojo.cc.tmpl and rebuilt mojo_nacl.
R=bradnelson@google.com, ncbray@chromium.org

Review URL: https://codereview.chromium.org/798733002

git-svn-id: svn://svn.chromium.org/native_client/trunk/src/native_client@14212 fcba33aa-ac0c-11dd-b9e7-8d5594d729c2

build/scan_sources.py

@@ -258,7 +258,7 @@ def Run(self):
       if added_dir:
         self.resolver.RemoveOneDirectory(scan_dir)
       scan_name = self.PopIfAvail()
-    return sorted(self.added_set)
+    return self.added_set
 
 
 def DoMain(argv):
@@ -288,7 +288,14 @@ def DoMain(argv):
   for filename in files:
     workQ.PushIfNew(filename)
 
-  sorted_list = workQ.Run()
+  sources_set = workQ.Run()
+
+  # If any of the original files requested aren't found, add them anyway.
+  # This is so that source files that will be generated are still returned in
+  # the program output.
+  sources_set = sources_set.union(set(files))
+
+  sorted_list = sorted(sources_set)
   return '\n'.join(sorted_list) + '\n'