Delete members of LIST which are `eq' to ELT, and return the result.
More precisely, this function skips any members `eq' to ELT at the
front of LIST, then removes members `eq' to ELT from the remaining
sublist by modifying its list structure, then returns the resulting
Write `(setq foo (delq element foo))' to be sure of correctly changing
the value of a list `foo'. (fn ELT LIST)