Add GN substitution support for Ninja's $in_newline

tools/gn/function_toolchain.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 <algorithm>
 
 #include "tools/gn/err.h"
 #include "tools/gn/functions.h"
 #include "tools/gn/parse_tree.h"
 #include "tools/gn/scheduler.h"
@@ skipping 557 matching lines @@
     "        The directory in the generated file and output directories,\n"
     "        respectively, for the current input file. If the source file\n"
     "        is in the same directory as the target is declared in, they will\n"
     "        will be the same as the \"target\" versions above.\n"
     "        Example: \"gen/base/test\"\n"
     "\n"
     "  Linker tools have multiple inputs and (potentially) multiple outputs\n"
     "  The following expansions are available:\n"
     "\n"
     "    {{inputs}}\n"
+    "    {{inputs_newline}}\n"
     "        Expands to the inputs to the link step. This will be a list of\n"
     "        object files and static libraries.\n"
     "        Example: \"obj/foo.o obj/bar.o obj/somelibrary.a\"\n"
     "\n"
+    "        The \"_newline\" version will separate the input files with\n"
+    "        newlines instead of spaces. This is useful in response files:\n"
+    "        some linkers can take a \"-filelist\" flag which expects newline\n"
+    "        separated files, and some Microsoft tools have a fixed-sized\n"
+    "        buffer for parsing each line of a response file.\n"
+    "\n"
     "    {{ldflags}}\n"
     "        Expands to the processed set of ldflags and library search paths\n"
     "        specified for the target.\n"
     "        Example: \"-m64, -fPIC -pthread -L/usr/local/mylib\"\n"
     "\n"
     "    {{libs}}\n"
     "        Expands to the list of system libraries to link to. Each will\n"
     "        be prefixed by the \"lib_prefix\".\n"
     "\n"
     "        As a special case to support Mac, libraries with names ending in\n"
@@ skipping 271 matching lines @@
     return Value();
 
   Scope::KeyValueMap values;
   block_scope.GetCurrentScopeValues(&values);
   toolchain->args() = values;
 
   return Value();
 }
 
 }  // namespace functions