cmake: Report enabled subsystem backends in a compact form. #7445

Job	Run time
Create test plan	5s
level1 / Haiku	1m 45s
level2 / Android (CMake, lean)	5m 21s
level2 / NetBSD	4m 10s
level2 / Ubuntu 22.04 (Intel Compiler)	4m 18s
level2 / GDK (MSVC, x64)	3m 51s
level2 / LoongArch64	4m 2s
level2 / OpenBSD	6m 34s
level2 / Windows (MSVC, clang-cl x64)	5m 21s
level2 / MacOS (GNU prefix)	4m 35s
level2 / Ubuntu 22.04	3m 28s
level2 / tvOS (CMake & xcode)	3m 31s
level2 / Android (Android.mk)	1m 39s
level2 / Sony PlayStation Vita (GLES w/ pib)	2m 53s
level2 / iOS (CMake & xcode)	3m 15s
level2 / Windows (msys2, mingw32)	4m 58s
level2 / Windows (msys2, clang64)	4m 30s
level2 / Windows (MSVC, ARM64)	4m 7s
level2 / Windows (msys2, ucrt64)	4m 17s
level2 / Steam Linux Runtime 3.0 (x86_64)	2m 50s
level2 / Nintendo 3DS	2m 21s
level2 / PowerPC	2m 22s
level2 / Windows (msys2, mingw64)	4m 20s
level2 / Ubuntu 22.04 (Intel oneAPI)	5m 27s
level2 / PowerPC64	2m 32s
level2 / Sony PlayStation Vita (GLES w/ PVR_PSP2)	2m 52s
level2 / Android (CMake)	6m 39s
level2 / N-Gage	4m 32s
level2 / Steam Linux Runtime 3.0 (arm64)	2m 14s
level2 / Emscripten	9m 2s
level2 / Ubuntu 24.04 (ARM64)	4m 26s
level2 / Sony PlayStation 2	6m 21s
level2 / MacOS (Framework) (x64)	7m 43s
level2 / RISC OS	1m 24s
level2 / Windows (MSVC, x64)	5m 43s
level2 / Android (Gradle)	2m 41s
level2 / Sony PlayStation Portable	4m 5s
level2 / Windows (MSVC, ARM)	4m 0s
level2 / Windows (MSVC, clang-cl x86)	5m 29s
level2 / MacOS (Framework) (arm64)	2m 57s
level2 / Windows (MSVC, x86)	5m 40s
level2 / FreeBSD	3m 5s
	2h 51m 25s

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