Add back kwargs

Summary:
Originally added in #17551 by dryganets but lost when an internal diff consolidated files into ReactNative/DEFS
Closes #17710

Differential Revision: D6778242

Pulled By: hramos

fbshipit-source-id: 22bd3348feccf1ecb53d897c84e1ca704e51fc33

ReactNative/DEFS

@@ -30,7 +30,7 @@ with allow_unsafe_import():
 
 # Building is not supported in OSS right now
 def rn_xplat_cxx_library(name, **kwargs):
-  cxx_library(name = name)
+  cxx_library(name = name, **kwargs)
 
 # Example: react_native_target('java/com/facebook/react/common:common')
 def react_native_target(path):