symlinks.c: small style cleanup

Add {}-braces around an else-part, where the if-part already has
{}-braces.

And, also remove some unnecessary "return;"-statements at the end of
"void foo()"-functions.

Signed-off-by: Kjetil Barvik <barvik@broadpark.no>
Signed-off-by: Junio C Hamano <gitster@pobox.com>