[mythtv] Master Qt5 builder error

[Gary Buhrmaster]

Has anyone else noticed that the buildbots
for Master Qt5 have been failing?  It appears that
the various compiler flags such as -fPIC are now
missing from the external/hdhomerun compile,
resulting in link errors.  If the blamelist is to be
believed, it appears to have been the FFMpeg
2.3.1 resync that caused the issue (and since
that commit changes configure, that seems like
a reasonable possibility).

I might eventually have time to look, but if an
expert has time first, that is obviously faster.

Gary