gn: Add runtime_link_output to tool("solib")

tools/gn/function_toolchain.cc

Index: tools/gn/function_toolchain.cc
diff --git a/tools/gn/function_toolchain.cc b/tools/gn/function_toolchain.cc
index 58532551d4f2d65250db6002fbaf675eec20cff7..fd75f6d53fb4c46082e2aacb8059311b6a8c764c 100644
--- a/tools/gn/function_toolchain.cc
+++ b/tools/gn/function_toolchain.cc
@@ -481,9 +481,10 @@ const char kTool_Help[] =
     "        that actually produces these files.\n"
     "\n"
     "        If you specify more than one output for shared library links,\n"
-    "        you should consider setting link_output and depend_output.\n"
-    "        Otherwise, the first entry in the outputs list should always be\n"
-    "        the main output which will be linked to.\n"
+    "        you should consider setting link_output, depend_output, and\n"
+    "        runtime_link_output. Otherwise, the first entry in the\n"
+    "        outputs list should always be the main output which will be\n"
+    "        linked to.\n"
     "\n"
     "        Example for a compiler tool that produces .obj files:\n"
     "          outputs = [\n"
@@ -503,19 +504,22 @@ const char kTool_Help[] =
     "\n"
     "    link_output  [string with substitutions]\n"
     "    depend_output  [string with substitutions]\n"
+    "    runtime_link_output  [string with substitutions]\n"
     "        Valid for: \"solink\" only (optional)\n"
     "\n"
-    "        These two files specify which of the outputs from the solink\n"
+    "        These three files specify which of the outputs from the solink\n"
     "        tool should be used for linking and dependency tracking. These\n"
     "        should match entries in the \"outputs\". If unspecified, the\n"
-    "        first item in the \"outputs\" array will be used for both. See\n"
+    "        first item in the \"outputs\" array will be used for all. See\n"
     "        \"Separate linking and dependencies for shared libraries\"\n"
-    "        below for more.\n"
+    "        below for more.  If link_output is set but runtime_link_output\n"
+    "        is not set, runtime_link_output defaults to link_output\n"
     "\n"
     "        On Windows, where the tools produce a .dll shared library and\n"
     "        a .lib import library, you will want both of these to be the\n"
-    "        import library. On Linux, if you're not doing the separate\n"
-    "        linking/dependency optimization, both of these should be the\n"
+    "        import library, while runtime_link_output should be set to the\n"
+    "        .dll file. On Linux, if you're not doing the separate\n"
+    "        linking/dependency optimization, all of these should be the\n"
     "        .so output.\n"
     "\n"
     "    output_prefix  [string]\n"
@@ -827,14 +831,16 @@ Value RunTool(Scope* scope,
       !ReadDepsFormat(&block_scope, tool.get(), err) ||
       !ReadPattern(&block_scope, "description", subst_validator, tool.get(),
                    &Tool::set_description, err) ||
-      !ReadString(&block_scope, "lib_switch", tool.get(),
-                  &Tool::set_lib_switch, err) ||
+      !ReadString(&block_scope, "lib_switch", tool.get(), &Tool::set_lib_switch,
+                  err) ||
       !ReadString(&block_scope, "lib_dir_switch", tool.get(),
                   &Tool::set_lib_dir_switch, err) ||
       !ReadPattern(&block_scope, "link_output", subst_validator, tool.get(),
                    &Tool::set_link_output, err) ||
       !ReadPattern(&block_scope, "depend_output", subst_validator, tool.get(),
                    &Tool::set_depend_output, err) ||
+      !ReadPattern(&block_scope, "runtime_link_output", subst_validator,
+                   tool.get(), &Tool::set_runtime_link_output, err) ||
       !ReadString(&block_scope, "output_prefix", tool.get(),
                   &Tool::set_output_prefix, err) ||
       !ReadPrecompiledHeaderType(&block_scope, tool.get(), err) ||