Add profiler option to SCons builds.

Add `tracy` option to `profiler`. If set, a tracy profiling client will be injected into the Godot binary.

# Conflicts:
#	platform/linuxbsd/godot_linuxbsd.cpp

platform/web/web_main.cpp

@@ -35,6 +35,7 @@
 #include "core/config/engine.h"
 #include "core/io/file_access.h"
 #include "core/io/resource_loader.h"
+#include "core/profiling/profiling.h"
 #include "main/main.h"
 #include "scene/main/scene_tree.h"
 #include "scene/main/window.h" // SceneTree only forward declares it.
@@ -126,6 +127,8 @@ void print_web_header() {
 
 /// When calling main, it is assumed FS is setup and synced.
 extern EMSCRIPTEN_KEEPALIVE int godot_web_main(int argc, char *argv[]) {
+	godot_init_profiler();
+
 	os = new OS_Web();
 
 #ifdef TOOLS_ENABLED