Patch for zero length malloc and check for malloc success

There is a feasible code path such that the string will
have a length of zero.  Malloc of a zero length has a
implementation dependent result (i.e. possible invalid
memory pointer).  Add one to the requested length to
eliminate the abiguity.  In addition, check the return
from malloc to insure it was successful.
(cherry picked from commit 28a77c36e2d320fa1304ad3822d5359b05af07a0)

Signed-off-by: Stuart Morgan <smorgan@mythtv.org>

Fixes #11570
Initialize chanid in mythtranscode

Static analysis (scan-build) detects that the variable
chanid could be used without initialization.  This is
actually a false positive, since the use is protected
by the found_chanid variable, but initializing the
variable should be benign, and eliminates that static
analysis detected issue.
(cherry picked from commit 49617bc0c174be8b58e37ded693aa8d037ba7975)

Signed-off-by: Stuart Morgan <smorgan@mythtv.org>

Fixes #11571
Check the return value of query.exec in dbutil.cpp

Fixes coverity 703634
(cherry picked from commit c45db226e673d4c890a092c7c76bc35266ec3996)

Signed-off-by: Stuart Morgan <smorgan@mythtv.org>

Fixes #11567
Workaround QT ISO date parsing issue in mythfilldatabase. Fixes #11538

Signed-off-by: Stuart Morgan <smorgan@mythtv.org>