Better document VkIcdSurface ABI in wsi.h #2929

Job	Run time
codegen	13s
linux-no-asm	3m 20s
linux (gcc, g++, Debug, ubuntu-20.04)	2m 49s
chromium	1m 21s
linux (gcc, g++, Debug, ubuntu-22.04)	3m 13s
linux-32 (Debug)	1m 54s
linux-32-no-asm	2m 8s
linux (gcc, g++, Release, ubuntu-20.04)	7m 13s
linux-32 (Release)	2m 22s
linux (gcc, g++, Release, ubuntu-22.04)	7m 8s
linux (clang, clang++, Debug, ubuntu-20.04)	2m 12s
linux (clang, clang++, Debug, ubuntu-22.04)	2m 54s
linux (clang, clang++, Release, ubuntu-20.04)	4m 9s
linux (clang, clang++, Release, ubuntu-22.04)	5m 12s
mingw-use-gas	1m 8s
windows_clang (clang, Debug)	3m 44s
windows_vs (Win32, Debug)	4m 6s
mingw	1m 56s
windows_clang (clang, Release)	3m 13s
windows_vs (Win32, Release)	4m 52s
windows_vs-no-asm (Win32)	4m 43s
windows_clang (clang-cl, Debug)	3m 50s
windows_vs (x64, Debug)	5m 7s
mingw-no-asm	1m 6s
windows_vs-no-asm (x64)	4m 31s
windows_clang (clang-cl, Release)	3m 57s
windows_vs (x64, Release)	4m 29s
mingw-no-asm-explicit	1m 7s
iOS	53s
tvOS	37s
mac (Debug, APPLE_STATIC_LOADER=ON)	4m 3s
Universal Binary Testing (STATIC ON) w/ Ninja	2m 1s
mac (Debug, APPLE_STATIC_LOADER=OFF)	4m 54s
Universal Binary Testing (STATIC ON) w/ Xcode	2m 30s
mac (Release, APPLE_STATIC_LOADER=ON)	4m 20s
Universal Binary Testing (STATIC OFF) w/ Ninja	1m 51s
mac (Release, APPLE_STATIC_LOADER=OFF)	5m 53s
Universal Binary Testing (STATIC OFF) w/ Xcode	2m 25s
	2h 3m 24s

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