adding copyright header

Summary: as in the title

Reviewed By: Croohand

Differential Revision: D30041822

fbshipit-source-id: 923158fcba241f5cd2ace8f87fa12083fd22356c

build/fbcode_builder/CMake/RustStaticLibrary.cmake

+# Copyright (c) Facebook, Inc. and its affiliates.
+
 include(FBCMakeParseArgs)
 
 set(
@@ -286,4 +288,4 @@ function(install_rust_static_library TARGET)
     RENAME ${staticlib_output_name}
     DESTINATION ${ARG_INSTALL_DIR}
   )
-endfunction()
\ No newline at end of file
+endfunction()