Fix one of egl::Context constructors incorrecly populating sharegroup #1445

Job	Run time
Android (Ubuntu)	10m 19s
cmake-build (Windows - MSVC 2022, windows-latest, Debug, cl, cl, Visual Studio 17 2022, -DIGL_WIT...	7m 40s
cmake-build (Windows - MSVC 2022 (no OpenGL), windows-latest, Debug, cl, cl, Visual Studio 17 202...	6m 16s
cmake-build (Ubuntu - Clang, ubuntu-latest, Debug, clang, clang++, Unix Makefiles, -DIGL_WITH_TRA...	7m 42s
cmake-build (Ubuntu - GCC, ubuntu-latest, Debug, gcc, g++, Unix Makefiles, -DIGL_WITH_TRACY=ON -D...	5m 5s
cmake-build (macOS - Clang (Xcode), macos-latest, Debug, clang, clang++, Xcode, -DIGL_WITH_VULKAN...	1h 13m 3s
cmake-build (macOS - Clang (Unix Makefiles), macos-latest, Debug, clang, clang++, Unix Makefiles,...	1h 12m 40s
	3h 2m 45s

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