Fix (rare) empty expression from skipped MacroInstantiation
Fix (rare) empty expression from skipped MacroInstantiation

ihnorton/Clang.jl,ihnorton/Clang.jl,zhmz90/Clang.jl,mdcfrancis/Clang.jl,JuliaPackageMirrors/Clang.jl,JuliaPackageMirrors/Clang.jl,mdcfrancis/Clang.jl,zhmz90/Clang.jl