IMPALA-875: Respect isAnalyzed_ in IntLiteral expressions

Partition column expressions are analysed twice for INSERT statements -
once to infer the type and so to add a possible cast, and once to
compute stats on the resulting expr. However, this process resulted in
an partition column expr that was a IntLiteral getting the smallest type
that would contains its value, rather than retaining the
column-compatible type that had been assigned to it.

This patch does the minimum thing, which is make IntLiteral.analyze()
idempotent. Doing the same thing to Expr and LiteralExpr unearths some
other bugs, which we will have to fix in a follow-on patch (see
IMPALA-884).

Change-Id: Ie22fc5d3f4832c735a1ebc0ef78f50d736f597fd
Reviewed-on: http://gerrit.ent.cloudera.com:8080/1931
Reviewed-by: Henry Robinson <henry@cloudera.com>
Tested-by: jenkins