llvm-build: Don't emit library information for disabled targets.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@156837 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/utils/llvm-build/llvmbuild/main.py b/utils/llvm-build/llvmbuild/main.py
index 2be9cd6..48b59bd 100644
--- a/utils/llvm-build/llvmbuild/main.py
+++ b/utils/llvm-build/llvmbuild/main.py
@@ -319,11 +319,16 @@
         # dependencies for added library groups.
         entries = {}
         for c in self.ordered_component_infos:
-            # Skip optional components which are not enabled
+            # Skip optional components which are not enabled.
             if c.type_name == 'OptionalLibrary' \
                 and c.name not in enabled_optional_components:
                 continue
 
+            # Skip target groups which are not enabled.
+            tg = c.get_parent_target_group()
+            if tg and not tg.enabled:
+                continue
+
             # Only certain components are in the table.
             if c.type_name not in ('Library', 'OptionalLibrary', \
                                    'LibraryGroup', 'TargetGroup'):