[mythtv] Problem with commit 9506b88 2017/10/09 : Cleanup gcc and clang warnings generated by -Wextra switch.

[Peter Bennett]

Hi David

The above mentioned commit is a merge of hundreds of changes. It is 
causing memory corruption errors on Raspberry Pi, consistently every 
time you try to play a recording. You get one of these errors and a core 
dump:

corrupted size vs prev size
smallbin double link list corrupted
free(): invalid pointer

These occur in malloc and free at different places each time. AMD64 
systems are not affected although the codebase is the same.

Compiling from aea96ba which is the immediately prior commit, is fine.
Compiling from 9506b88 which is immediately after that commit, gives 
those errors, as does compiling from the latest.

I cannot compile any of the intermediate commits between those two, 
because they are off your repository, do not contain the Raspberry Pi 
Stretch changes, and thus fail compilation.

Do you know which change may be causing this problem? We may have to 
roll back this set of changes.

Peter