Switch header convention from #include "SDL.h" to #include <SDL3/SDLh>

I ran this script in the include directory:
```sh
sed -i '' -e 's,#include "\(SDL.*\)",#include <SDL3/\1>,' *.h
```

I ran this script in the src directory:
```sh
for i in ../include/SDL3/SDL*.h
do hdr=$(basename $i)
   if [ x"$(echo $hdr | egrep 'SDL_main|SDL_name|SDL_test|SDL_syswm|SDL_opengl|SDL_egl|SDL_vulkan')" != x ]; then
        find . -type f -exec sed -i '' -e 's,#include "\('$hdr'\)",#include <SDL3/\1>,' {} \;
    else
        find . -type f -exec sed -i '' -e '/#include "'$hdr'"/d' {} \;
    fi
done
```

Fixes https://github.com/libsdl-org/SDL/issues/6575

include/SDL3/SDL_touch.h

@@ -0,0 +1,150 @@
+/*
+  Simple DirectMedia Layer
+  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
+  arising from the use of this software.
+
+  Permission is granted to anyone to use this software for any purpose,
+  including commercial applications, and to alter it and redistribute it
+  freely, subject to the following restrictions:
+
+  1. The origin of this software must not be misrepresented; you must not
+     claim that you wrote the original software. If you use this software
+     in a product, an acknowledgment in the product documentation would be
+     appreciated but is not required.
+  2. Altered source versions must be plainly marked as such, and must not be
+     misrepresented as being the original software.
+  3. This notice may not be removed or altered from any source distribution.
+*/
+
+/**
+ *  \file SDL_touch.h
+ *
+ *  Include file for SDL touch event handling.
+ */
+
+#ifndef SDL_touch_h_
+#define SDL_touch_h_
+
+#include <SDL3/SDL_stdinc.h>
+#include <SDL3/SDL_error.h>
+#include <SDL3/SDL_video.h>
+
+#include <SDL3/begin_code.h>
+/* Set up for C function definitions, even when using C++ */
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef Sint64 SDL_TouchID;
+typedef Sint64 SDL_FingerID;
+
+typedef enum
+{
+    SDL_TOUCH_DEVICE_INVALID = -1,
+    SDL_TOUCH_DEVICE_DIRECT,            /* touch screen with window-relative coordinates */
+    SDL_TOUCH_DEVICE_INDIRECT_ABSOLUTE, /* trackpad with absolute device coordinates */
+    SDL_TOUCH_DEVICE_INDIRECT_RELATIVE  /* trackpad with screen cursor-relative coordinates */
+} SDL_TouchDeviceType;
+
+typedef struct SDL_Finger
+{
+    SDL_FingerID id;
+    float x;
+    float y;
+    float pressure;
+} SDL_Finger;
+
+/* Used as the device ID for mouse events simulated with touch input */
+#define SDL_TOUCH_MOUSEID ((Uint32)-1)
+
+/* Used as the SDL_TouchID for touch events simulated with mouse input */
+#define SDL_MOUSE_TOUCHID ((Sint64)-1)
+
+
+/**
+ * Get the number of registered touch devices.
+ *
+ * On some platforms SDL first sees the touch device if it was actually used.
+ * Therefore SDL_GetNumTouchDevices() may return 0 although devices are
+ * available. After using all devices at least once the number will be
+ * correct.
+ *
+ * This was fixed for Android in SDL 2.0.1.
+ *
+ * \returns the number of registered touch devices.
+ *
+ * \since This function is available since SDL 3.0.0.
+ *
+ * \sa SDL_GetTouchDevice
+ */
+extern DECLSPEC int SDLCALL SDL_GetNumTouchDevices(void);
+
+/**
+ * Get the touch ID with the given index.
+ *
+ * \param index the touch device index
+ * \returns the touch ID with the given index on success or 0 if the index is
+ *          invalid; call SDL_GetError() for more information.
+ *
+ * \since This function is available since SDL 3.0.0.
+ *
+ * \sa SDL_GetNumTouchDevices
+ */
+extern DECLSPEC SDL_TouchID SDLCALL SDL_GetTouchDevice(int index);
+
+/**
+ * Get the touch device name as reported from the driver or NULL if the index
+ * is invalid.
+ *
+ * \since This function is available since SDL 3.0.0.
+ */
+extern DECLSPEC const char* SDLCALL SDL_GetTouchName(int index);
+
+/**
+ * Get the type of the given touch device.
+ *
+ * \since This function is available since SDL 3.0.0.
+ */
+extern DECLSPEC SDL_TouchDeviceType SDLCALL SDL_GetTouchDeviceType(SDL_TouchID touchID);
+
+/**
+ * Get the number of active fingers for a given touch device.
+ *
+ * \param touchID the ID of a touch device
+ * \returns the number of active fingers for a given touch device on success
+ *          or 0 on failure; call SDL_GetError() for more information.
+ *
+ * \since This function is available since SDL 3.0.0.
+ *
+ * \sa SDL_GetTouchFinger
+ */
+extern DECLSPEC int SDLCALL SDL_GetNumTouchFingers(SDL_TouchID touchID);
+
+/**
+ * Get the finger object for specified touch device ID and finger index.
+ *
+ * The returned resource is owned by SDL and should not be deallocated.
+ *
+ * \param touchID the ID of the requested touch device
+ * \param index the index of the requested finger
+ * \returns a pointer to the SDL_Finger object or NULL if no object at the
+ *          given ID and index could be found.
+ *
+ * \since This function is available since SDL 3.0.0.
+ *
+ * \sa SDL_RecordGesture
+ */
+extern DECLSPEC SDL_Finger * SDLCALL SDL_GetTouchFinger(SDL_TouchID touchID, int index);
+
+/* Ends C function definitions when using C++ */
+#ifdef __cplusplus
+}
+#endif
+#include <SDL3/close_code.h>
+
+#endif /* SDL_touch_h_ */
+
+/* vi: set ts=4 sw=4 expandtab: */