Fix the CLD2 GN build on the Mac.

third_party/cld_2/BUILD.gn

Index: third_party/cld_2/BUILD.gn
diff --git a/third_party/cld_2/BUILD.gn b/third_party/cld_2/BUILD.gn
index 52b016af70b1ed2f1b91ea3f26c1d4647b158c11..268eced897ad6995b50e8d542b412f1d55eaaf76 100644
--- a/third_party/cld_2/BUILD.gn
+++ b/third_party/cld_2/BUILD.gn
@@ -92,7 +92,7 @@ source_set("cld2_data") {
 # As in the corresponding gyp file, this just builds the core interfaces for
 # CLD2. You must still declare a dependency on a specific data set, either
 # cld2_dynamic or cld2_static. 
-static_library("cld_2") {
+source_set("cld_2") {

[Dirk Pranke, 2014/11/12 02:46:04]

Both this target and the one below have no actual object files. On the mac, this
isn't allowed (libtool explodes).

In GYP, we work around this in the generator by checking to see if there are any
input object files, and if there aren't, we set the target to type 'none'
instead of type 'static library'.

This, however, seems like a misfeature.

Changing this to a source set works, but seems like it might also be the wrong
way to do things. We could change this to a 'group', but groups probably can't
have 'sources' (which in this case only include headers).

Brett, what do you think the right thing to do here is?

   sources = core_files
   include_dirs = [
     "src/internal",
@@ -108,7 +108,7 @@ static_library("cld_2") {
 }
 
 
-static_library("cld2_platform_impl") {
+source_set("cld2_platform_impl") {
   # TODO: Make this something that can be overridden
   deps = [ ":cld2_static" ]
 }