Fix SQL DDL generation

Query parameters are being matched only based on their name. If one
parameter starts with the name of another, this leads to conflicts, e.g.
:payeeId and :payeeIdentifier --> if both matches are replaced by NULL,
this results in the second match being replaced to NULLentifier, which
is obviously not intended.

This commit superseeds commit f0caa56b.

(cherry-picked from commit b4061d79)

REVIEW: 129796
BUG:378676
FIXED-IN:4.8.1

# Conflicts:
#	kmymoney/mymoney/storage/mymoneydbdef.cpp