Style: Enforce braces around if blocks and loops

Using clang-tidy's `readability-braces-around-statements`.
https://clang.llvm.org/extra/clang-tidy/checks/readability-braces-around-statements.html

platform/linuxbsd/godot_linuxbsd.cpp

@@ -51,8 +51,9 @@ int main(int argc, char *argv[]) {
 		return 255;
 	}
 
-	if (Main::start())
+	if (Main::start()) {
 		os.run(); // it is actually the OS that decides how to run
+	}
 	Main::cleanup();
 
 	if (ret) { // Previous getcwd was successful