Add SDL_PROP_IOSTREAM_MEM_BASE_POINTER #31

Job	Run time
Create test plan	4s
level1 / Haiku	1m 45s
level2 / Windows (MSVC, clang-cl x64)	6m 36s
level2 / Windows (msys2, ucrt64)	8m 35s
level2 / Android (Android.mk)	2m 6s
level2 / Sony PlayStation 2	4m 41s
level2 / Emscripten	9m 2s
level2 / MacOS (GNU prefix)	4m 17s
level2 / Android (Gradle)	2m 4s
level2 / Nintendo 3DS	1m 53s
level2 / Windows (MSVC, ARM64)	3m 3s
level2 / RISC OS	1m 16s
level2 / Windows (MSVC, x86)	4m 11s
level2 / tvOS (CMake & xcode)	2m 4s
level2 / Windows (msys2, mingw32)	8m 43s
level2 / NetBSD	2m 38s
level2 / GDK (MSVC, x64)	2m 39s
level2 / Ubuntu 20.04 (Intel Compiler)	4m 30s
level2 / Sony PlayStation Vita (GLES w/ PVR_PSP2)	3m 4s
level2 / Windows (msys2, clang64)	5m 55s
level2 / Windows (MSVC, clang-cl x86)	4m 31s
level2 / Ubuntu 20.04	4m 17s
level2 / iOS (CMake & xcode)	2m 11s
level2 / Ubuntu 22.04	4m 31s
level2 / Windows (msys2, clang32)	7m 31s
level2 / Android (CMake, lean)	4m 11s
level2 / Sony PlayStation Portable	3m 31s
level2 / PowerPC64	1m 53s
level2 / Ubuntu 20.04 (Intel oneAPI)	6m 18s
level2 / Android (CMake)	6m 20s
level2 / FreeBSD	3m 1s
level2 / Windows (MSVC, ARM)	3m 18s
level2 / Windows (msys2, mingw64)	8m 41s
level2 / MacOS (Framework) (x64)	4m 25s
level2 / Windows (MSVC, x64)	4m 21s
level2 / Sony PlayStation Vita (GLES w/ pib)	3m 6s
level2 / MacOS (Framework) (arm64)	3m 8s
level2 / LoongArch64	2m 49s
	2h 37m 9s

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