[CA-115744] [SCTX-1538] Do not treat DbgPrint strings as format strings

Our hook for DbgPrint messages was passing these messages as the
format parameter into a printf statement.  If there was a %s or
similar in the string we would then deference the next argument on
the stack, leading to a potential BSOD.

Signed-off-by: Ben Chalmers <Ben.Chalmers@citrix.com>