egl: fix gcc warning braces around scalar initializer
egl: fix gcc warning braces around scalar initializer

Reviewed-by: Alejandro Piñeiro <5dfedca1889afcca58e9b95acd46f78f54f166ed@igalia.com>

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler