GDK: Fix standalone library build #764

Job	Run time
Rocky Linux MinGW	1m 57s
FreeBSD	1m 8s
Rocky Linux MinGW SDL3	1m 7s
iOS/tvOS SDL3 (iOS, iphoneos, arm64)	44s
iOS/tvOS SDL3 (iOS, iphonesimulator, x86_64;arm64)	1m 2s
Rocky Linux	1m 53s
Debian Linux PPC	1m 52s
iOS/tvOS SDL3 (tvOS, appletvos, arm64)	57s
Debian Linux PPC SDL3	59s
Rocky Linux SDL3	1m 19s
iOS/tvOS SDL3 (tvOS, appletvsimulator, x86_64;arm64)	1m 6s
macOS (x86_64)	27s
macOS (Universal) SDL3	1m 40s
Windows (MSVC)	1m 11s
	17m 22s

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