GDK: Fix standalone library build #366

Job	Run time
Rocky Linux	1m 49s
Rocky Linux MinGW	52s
FreeBSD	1m 8s
iOS/tvOS SDL3 (iOS, iphoneos, arm64)	46s
Debian Linux PPC	1m 42s
Rocky Linux MinGW SDL3	49s
iOS/tvOS SDL3 (iOS, iphonesimulator, x86_64;arm64)	54s
iOS/tvOS SDL3 (tvOS, appletvos, arm64)	39s
Rocky Linux SDL3	1m 16s
iOS/tvOS SDL3 (tvOS, appletvsimulator, x86_64;arm64)	1m 17s
Debian Linux PPC SDL3	56s
macOS (x86_64)	27s
macOS (Universal) SDL3	1m 17s
Windows (MSVC)	33s
Windows (MSVC) SDL3	41s
	15m 6s

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