HPCC-9909 Typos in compiler error messages

Corrects spelling and grammer in the files ecl/hql/hqlgram.y and
ecl/hql/hqlgram2.cpp regarding several error messages.

Signed-off-by: jamienoss <james.noss@lexisnexis.com>
Merge pull request #4795 from jamienoss/issue9909

HPCC-9909 Typos in compiler error messages

Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>