graphics: rewrite screenshot and api capture image processing (#870)

## Link to GitHub Issue or related Pull Request, if one exists
#0

## Description of change
Significantly speeds up API screen capture and D3D9 screenshots saving.
Two reasons for doing this:

1. We now have a 4K game (GITADORA) and existing capture code was taking
multiple seconds.
2. Renewed user interest on streaming as we have a couple more companion
apps in active development.

**API screen capture (streaming), 1280x720:** 14.3ms -> 6.3ms per frame.
Back buffer copies go to pooled `D3DPOOL_SYSTEMMEM` surfaces via
`GetRenderTargetData` instead of allocating a lockable render target
every frame, and TooJpeg is replaced with libjpeg-turbo (encode 9.8ms ->
3.0ms). MSAA remains unsupported

**Screenshots for GITADORA arena model, across 4 screens with one of
them 4K**: 4068ms -> 124ms. `D3DXSaveSurfaceToFileA` is replaced with
fpng (encode 4043ms -> 76ms) and the screens encode in parallel.
Dropping D3DX also removes the `d3dx9_43.dll` ... `d3dx9_24.dll` probing
loop, so screenshots no longer fail outright on machines with no D3DX9
runtime installed.

Screenshot surfaces are read on the present thread, so no D3D call
reaches another thread for screenshots. This fixes a hang in DDR X2
introduced earlier in the branch: its device has no internal locking,
and reading the surface on a pool thread while the present thread sat
inside `GetRenderTargetData` left the game's own render thread
deadlocked.


## Testing

- **GITADORA** (arena model, D3D9Ex, 4K main plus three subscreens,
windowed) with
`-screenshotsub`: three sets of four screenshots, images verified
correct. Completion
order differs between sets, so the screens really are encoding in
parallel.
- **LovePlus** (KLP, plain D3D9, 768x1360): covers the inline path used
by games whose
  image processing must not leave the present thread. 
- **API screen capture** through a companion app: live video correct
throughout.
- **Print Screen** bound as the screenshot key: the clipboard copy
succeeded on every shot.
- Quitting the game after capturing leaves no `IDirect3DDevice9`
reference count warning,
  so the pooled readback surfaces are released along with the device.

src/spice2x/licenses.txt

@@ -527,25 +527,78 @@ HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABI
 TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
 EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-toojpeg (zlib)
+fpng (Unlicense)
 -------------------------------------------
-zlib License
+Copyright (c) 2021 Richard Geldreich, Jr.
+Incorporates public domain code by Alex Evans, the original miniz by
+Richard Geldreich, Jr., and Huffman code size work by Alistair Moffat and
+Jyrki Katajainen.
 
-Copyright (c) 2011-2016 Stephan Brumme
+This is free and unencumbered software released into the public domain.
 
-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
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-   an acknowledgment in the product documentation would be appreciated but is
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-3. This notice may not be removed or altered from any source distribution.
+Anyone is free to copy, modify, publish, use, compile, sell, or distribute
+this software, either in source code form or as a compiled binary, for any
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+
+libjpeg-turbo (IJG)
+-------------------------------------------
+This software is based in part on the work of the Independent JPEG Group.
+
+Only the libjpeg API library is used here. Per the libjpeg-turbo licensing
+terms that portion is covered by the IJG License, reproduced below; the SIMD
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+License covers the TurboJPEG API library and build system, neither of which is
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+with respect to this software, its quality, accuracy, merchantability, or
+fitness for a particular purpose.  This software is provided "AS IS", and you,
+its user, assume the entire risk as to its quality and accuracy.
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+This software is copyright (C) 1991-2020, Thomas G. Lane, Guido Vollbeding.
+All Rights Reserved except as specified below.
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+Permission is hereby granted to use, copy, modify, and distribute this
+software (or portions thereof) for any purpose, without fee, subject to these
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 robin_hood.h (MIT)
 -------------------------------------------