Update to SDL 2.24.0 and add separate macOS UB2 dylib

Update mingw and macOS SDL libraries to 2.24.0. (MSVC .lib files and
Xcode project haven't been updated.)

There is now a separate SDL dylib for macOS Universal Binary 1 and 2
because SDL 2.24.0 dropped support for macOS 10.6 (which is last to
support x86). Documentation says SDL 2.24.0 also dropped macOS 10.7
and 10.8 too. So UB2 is now 10.9 or later while 10.5 to 10.8 live in
UB1.

Compiled using osxcross with macOS 11.3 SDK. Ran "strip -x" on Windows
and macOS libraries. Ad-hoc signed dylib using PyOxidizer rcodesign to
fix digest checksums after strip.

code/SDL2/include/SDL_test_font.h

@@ -1,6 +1,6 @@
 /*
   Simple DirectMedia Layer
-  Copyright (C) 1997-2018 Sam Lantinga <slouken@libsdl.org>
+  Copyright (C) 1997-2022 Sam Lantinga <slouken@libsdl.org>
 
   This software is provided 'as-is', without any express or implied
   warranty.  In no event will the authors be held liable for any damages
@@ -38,7 +38,8 @@ extern "C" {
 
 /* Function prototypes */
 
-#define FONT_CHARACTER_SIZE  8
+#define FONT_CHARACTER_SIZE 8
+#define FONT_LINE_HEIGHT    (FONT_CHARACTER_SIZE + 2)
 
 /**
  *  \brief Draw a string in the currently set font.
@@ -48,22 +49,108 @@ extern "C" {
  *  \param y The Y coordinate of the upper left corner of the character.
  *  \param c The character to draw.
  *
- *  \returns Returns 0 on success, -1 on failure.
+ *  \returns 0 on success, -1 on failure.
  */
-int SDLTest_DrawCharacter(SDL_Renderer *renderer, int x, int y, char c);
+int SDLTest_DrawCharacter(SDL_Renderer *renderer, int x, int y, Uint32 c);
 
 /**
- *  \brief Draw a string in the currently set font.
+ *  \brief Draw a UTF-8 string in the currently set font.
+ *
+ *  The font currently only supports characters in the Basic Latin and Latin-1 Supplement sets.
  *
  *  \param renderer The renderer to draw on.
  *  \param x The X coordinate of the upper left corner of the string.
  *  \param y The Y coordinate of the upper left corner of the string.
  *  \param s The string to draw.
  *
- *  \returns Returns 0 on success, -1 on failure.
+ *  \returns 0 on success, -1 on failure.
  */
 int SDLTest_DrawString(SDL_Renderer *renderer, int x, int y, const char *s);
 
+/**
+ *  \brief Data used for multi-line text output
+ */
+typedef struct SDLTest_TextWindow
+{
+    SDL_Rect rect;
+    int current;
+    int numlines;
+    char **lines;
+} SDLTest_TextWindow;
+
+/**
+ *  \brief Create a multi-line text output window
+ *
+ *  \param x The X coordinate of the upper left corner of the window.
+ *  \param y The Y coordinate of the upper left corner of the window.
+ *  \param w The width of the window (currently ignored)
+ *  \param h The height of the window (currently ignored)
+ *
+ *  \returns the new window, or NULL on failure.
+ *
+ *  \since This function is available since SDL 2.24.0
+ */
+SDLTest_TextWindow *SDLTest_TextWindowCreate(int x, int y, int w, int h);
+
+/**
+ *  \brief Display a multi-line text output window
+ *
+ *  This function should be called every frame to display the text
+ *
+ *  \param textwin The text output window
+ *  \param renderer The renderer to use for display
+ *
+ *  \since This function is available since SDL 2.24.0
+ */
+void SDLTest_TextWindowDisplay(SDLTest_TextWindow *textwin, SDL_Renderer *renderer);
+
+/**
+ *  \brief Add text to a multi-line text output window
+ *
+ *  Adds UTF-8 text to the end of the current text. The newline character starts a
+ *  new line of text. The backspace character deletes the last character or, if the
+ *  line is empty, deletes the line and goes to the end of the previous line.
+ *
+ *  \param textwin The text output window
+ *  \param fmt A printf() style format string
+ *  \param ...  additional parameters matching % tokens in the `fmt` string, if any
+ *
+ *  \since This function is available since SDL 2.24.0
+ */
+void SDLTest_TextWindowAddText(SDLTest_TextWindow *textwin, SDL_PRINTF_FORMAT_STRING const char *fmt, ...) SDL_PRINTF_VARARG_FUNC(2);
+
+/**
+ *  \brief Add text to a multi-line text output window
+ *
+ *  Adds UTF-8 text to the end of the current text. The newline character starts a
+ *  new line of text. The backspace character deletes the last character or, if the
+ *  line is empty, deletes the line and goes to the end of the previous line.
+ *
+ *  \param textwin The text output window
+ *  \param text The text to add to the window
+ *  \param len The length, in bytes, of the text to add to the window
+ *
+ *  \since This function is available since SDL 2.24.0
+ */
+void SDLTest_TextWindowAddTextWithLength(SDLTest_TextWindow *textwin, const char *text, size_t len);
+
+/**
+ *  \brief Clear the text in a multi-line text output window
+ *
+ *  \param textwin The text output window
+ *
+ *  \since This function is available since SDL 2.24.0
+ */
+void SDLTest_TextWindowClear(SDLTest_TextWindow *textwin);
+
+/**
+ *  \brief Free the storage associated with a multi-line text output window
+ *
+ *  \param textwin The text output window
+ *
+ *  \since This function is available since SDL 2.24.0
+ */
+void SDLTest_TextWindowDestroy(SDLTest_TextWindow *textwin);
 
 /**
  *  \brief Cleanup textures used by font drawing functions.