CDB: Only use codemodel breakpoint correction for old cdbs.

Since version 6.2 cdb supports setting breakpoints on non
codelines and automatically set it to the next available line.

Change-Id: I27facf4f2463bad76a20ef0abb5a5412471c296f
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
CDB: Handle "ambiguous symbol" messages on breakpoint inserts.

These messages usually appear when there is a lambda at the position
the breakpoint is about to be inserted.

Task-number: QTCREATORBUG-12178
Task-number: QTCREATORBUG-12016
Change-Id: I20f7b0e900147030bfd08206fab869ac22810825
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
Reviewed-by: hjk <hjk121@nokiamail.com>