gn: Mention complete_static_lib in `gn help static_library`.

tools/gn/functions_target.cc

 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "tools/gn/functions.h"
 
 #include "tools/gn/config_values_generator.h"
 #include "tools/gn/err.h"
 #include "tools/gn/parse_tree.h"
 #include "tools/gn/scope.h"
@@ skipping 638 matching lines @@
     "static_library: Declare a static library target.\n"
     "\n"
     "  Make a \".a\" / \".lib\" file.\n"
     "\n"
     "  If you only need the static library for intermediate results in the\n"
     "  build, you should consider a source_set instead since it will skip\n"
     "  the (potentially slow) step of creating the intermediate library file.\n"
     "\n"
     "Variables\n"
     "\n"
+    "complete_static_lib\n"
     CONFIG_VALUES_VARS_HELP
     DEPS_VARS
     DEPENDENT_CONFIG_VARS
     GENERAL_TARGET_VARS;
 
 Value RunStaticLibrary(Scope* scope,
                        const FunctionCallNode* function,
                        const std::vector<Value>& args,
                        BlockNode* block,
                        Err* err) {
@@ skipping 58 matching lines @@
   const Template* templ = scope->GetTemplate(target_type);
   if (templ)
     return templ->Invoke(scope, function, sub_args, block, err);
 
   // Otherwise, assume the target is a built-in target type.
   return ExecuteGenericTarget(target_type.c_str(), scope, function, sub_args,
                               block, err);
 }
 
 }  // namespace functions