bundleloader.h, which is included if MACOS is defined, defines
inline functions that reference bundle loading system functions,
which requires linking to the core foundation framework.
Avoid requiring linking to extra libraries/frameworks if
NO_DYNAMIC_VP is defined.
For the first encoded frame, is bEncCurFrmAsIdrFlag true
while bIdrPeriodFlag is false.
Previously, the scene detection code unnecessarily checked for
a scene change in the first encoded frame (where the reference
frame was an uninitialized frame), triggering valgrind warnings
about using uninitialized memory.
The same ifdefs are already used in the corresponding constructors,
so this just avoids a runtime/link time library dependency which
is practically unused in this build setup.
