Use gold during nat compile if possible

gold.diff

--- Engine/Source/Developer/SourceControl/SourceControl.Build.cs	2017-01-31 04:06:01.000000000 -0500
@@ -14,20 +14,17 @@
 				"CoreUObject",
 				"InputCore",
 			}
 		);
 
-		if (Target.Platform != UnrealTargetPlatform.Linux)
-		{
-			PrivateDependencyModuleNames.AddRange(
-				new string[] {
-					"Slate",
-					"SlateCore",
-                    "EditorStyle"
-				}
-			);
-		}
+		PrivateDependencyModuleNames.AddRange(
+			new string[] {
+				"Slate",
+				"SlateCore",
+				"EditorStyle"
+			}
+		);
 
         if (UEBuildConfiguration.bBuildEditor)
         {
 			PrivateDependencyModuleNames.AddRange(
                 new string[] {
--- Engine/Source/Programs/UnrealBuildTool/Linux/LinuxToolChain.cs	2017-02-10 03:28:09.000000000 -0500
@@ -29,11 +29,13 @@
 					if (!String.IsNullOrEmpty(ClangPath))
 					{
 						break;
 					}
 				}
-				GCCPath = Which("g++");
+				// gcc is not really supported at this point, uncomment when/if the support is repaired
+				//GCCPath = Which("g++");
+				GoldPath = Which("ld.gold");
 				ArPath = Which("ar");
 				RanlibPath = Which("ranlib");
 				StripPath = Which("strip");
 
 				// if clang is available, zero out gcc (@todo: support runtime switching?)
@@ -568,10 +570,16 @@
 
 		string GetLinkArguments(LinkEnvironment LinkEnvironment)
 		{
 			string Result = "";
 
+			// use gold if possible
+			if (!String.IsNullOrEmpty(GoldPath))
+			{
+				Result += " -fuse-ld=gold";
+			}
+
 			// debugging symbols
 			// Applying to all configurations @FIXME: temporary hack for FN to enable callstack in Shipping builds (proper resolution: UEPLAT-205)
 			Result += " -rdynamic";   // needed for backtrace_symbols()...
 
 			if (LinkEnvironment.bIsBuildingDLL)
@@ -677,14 +685,15 @@
 			// Write output
 			string ConvertedExpression = "  " + ConvertedFilePath + "(" + ConvertedLineNumber + "," + ConvertedColumnNumber + "):" + MatchDescription;
 			Console.WriteLine(ConvertedExpression); // To create clickable vs link
 		}
 
-		// cache the location of NDK tools
+		// cache the location of tools
 		static string BaseLinuxPath;
 		static string ClangPath;
 		static string GCCPath;
+		static string GoldPath;
 		static string ArPath;
 		static string RanlibPath;
 		static string StripPath;
 
 		/// <summary>
--- Engine/Source/Runtime/Launch/Launch.Build.cs	2017-02-09 18:41:45.000000000 -0500
@@ -142,10 +142,11 @@
 			PublicIncludePathModuleNames.Add("ProfilerClient");
 
 			PrivateDependencyModuleNames.AddRange(
 				new string[] {
 					"SourceControl",
+					"EditorStyle",	// A module that uses SourceControl module on Linux will also depend directly on EditorStyle
 					"UnrealEd",
 					"DesktopPlatform"
 				}
 			);