Fix: position() after skip() did not report correct position.

Same fix as in https://github.com/JuliaLang/julia/commit/47dd251ffbbcb4dd9813d0bd1db8dc3f63c3a374#src/support/ios.c and https://github.com/JuliaLang/julia/commit/5482a049f2106caf871480037b0d1d609984f992#src/support/ios.c but this time for skip(). I believe this is the last occurence.