SCons: Add production=yes option to use production defaults

This is meant for users making custom builds to match the options used on
optimized, official builds.

This enables, on the platforms which support them:
- `use_static_cpp=yes` (portable binaries for Linux and Windows)
- `use_lto=yes` (link time optimizations - note: requires a lot of RAM!)
- `debug_symbols=no` (no debug symbols, smaller binaries)

Also abort when using MSVC with `production=yes`, as:
- It cannot optimize the GDScript VM like GCC or Clang do, leading to
  significant performance drops.
- Its LTO support is unreliable, at least used to trigger crashes last
  we tried it extensively.

All options can still be overridden if specified, and the `dev=yes` option
was changed to also support overrides.

SConstruct

@@ -105,15 +105,14 @@ if profile:
 opts = Variables(customs, ARGUMENTS)
 
 # Target build options
-opts.Add("arch", "Platform-dependent architecture (arm/arm64/x86/x64/mips/...)", "")
-opts.Add(EnumVariable("bits", "Target platform bits", "default", ("default", "32", "64")))
 opts.Add("p", "Platform (alias for 'platform')", "")
 opts.Add("platform", "Target platform (%s)" % ("|".join(platform_list),), "")
-opts.Add(EnumVariable("target", "Compilation target", "debug", ("debug", "release_debug", "release")))
-opts.Add(EnumVariable("optimize", "Optimization type", "speed", ("speed", "size")))
-
 opts.Add(BoolVariable("tools", "Build the tools (a.k.a. the Godot editor)", True))
-opts.Add(BoolVariable("tests", "Build the unit tests", False))
+opts.Add(EnumVariable("target", "Compilation target", "debug", ("debug", "release_debug", "release")))
+opts.Add("arch", "Platform-dependent architecture (arm/arm64/x86/x64/mips/...)", "")
+opts.Add(EnumVariable("bits", "Target platform bits", "default", ("default", "32", "64")))
+opts.Add(EnumVariable("optimize", "Optimization type", "speed", ("speed", "size")))
+opts.Add(BoolVariable("production", "Set defaults to build Godot for use in production", False))
 opts.Add(BoolVariable("use_lto", "Use link-time optimization", False))
 
 # Components
@@ -123,11 +122,12 @@ opts.Add(BoolVariable("xaudio2", "Enable the XAudio2 audio driver", False))
 opts.Add("custom_modules", "A list of comma-separated directory paths containing custom modules to build.", "")
 
 # Advanced options
-opts.Add(BoolVariable("verbose", "Enable verbose output for the compilation", False))
+opts.Add(BoolVariable("dev", "If yes, alias for verbose=yes warnings=extra werror=yes", False))
 opts.Add(BoolVariable("progress", "Show a progress indicator during compilation", True))
+opts.Add(BoolVariable("tests", "Build the unit tests", False))
+opts.Add(BoolVariable("verbose", "Enable verbose output for the compilation", False))
 opts.Add(EnumVariable("warnings", "Level of compilation warnings", "all", ("extra", "all", "moderate", "no")))
 opts.Add(BoolVariable("werror", "Treat compiler warnings as errors", False))
-opts.Add(BoolVariable("dev", "If yes, alias for verbose=yes warnings=extra werror=yes", False))
 opts.Add("extra_suffix", "Custom extra suffix added to the base filename of all generated binary files", "")
 opts.Add(BoolVariable("vsproj", "Generate a Visual Studio solution", False))
 opts.Add(BoolVariable("disable_3d", "Disable 3D nodes for a smaller executable", False))
@@ -317,12 +317,34 @@ if selected_platform in platform_list:
         env.Tool("compilation_db")
         env.Alias("compiledb", env.CompilationDatabase())
 
+    # 'dev' and 'production' are aliases to set default options if they haven't been set
+    # manually by the user. We use `ARGUMENTS.get()` to check if they were manually set.
     if env["dev"]:
-        env["verbose"] = True
-        env["warnings"] = "extra"
-        env["werror"] = True
+        env["verbose"] = ARGUMENTS.get("verbose", True)
+        env["warnings"] = ARGUMENTS.get("warnings", "extra")
+        env["werror"] = ARGUMENTS.get("werror", True)
         if env["tools"]:
-            env["tests"] = True
+            env["tests"] = ARGUMENTS.get("tests", True)
+    if env["production"]:
+        env["use_static_cpp"] = ARGUMENTS.get("use_static_cpp", True)
+        env["use_lto"] = ARGUMENTS.get("use_lto", True)
+        env["debug_symbols"] = ARGUMENTS.get("debug_symbols", False)
+        if not env["tools"] and env["target"] == "debug":
+            print(
+                "WARNING: Requested `production` build with `tools=no target=debug`, "
+                "this will give you a full debug template (use `target=release_debug` "
+                "for an optimized template with debug features)."
+            )
+        if env.msvc:
+            print(
+                "WARNING: For `production` Windows builds, you should use MinGW with GCC "
+                "or Clang instead of Visual Studio, as they can better optimize the "
+                "GDScript VM in a very significant way. MSVC LTO also doesn't work "
+                "reliably for our use case."
+                "If you want to use MSVC nevertheless for production builds, set "
+                "`debug_symbols=no use_lto=no` instead of the `production=yes` option."
+            )
+            Exit(255)
 
     env.extra_suffix = ""