media/mtp: Add missing LOCAL_C_INCLUDES

One of the source files here is including <cutils/tztime.h> which
itself includes <bionic_time.h>, a private C library header used
to define the strftime_tz() extension (which used to be declared
in <time.h> but was moved there instead).

Add a missing C include path to let our code compile as usual.

Change-Id: I6aac2f1d3d15ad182679c81ff3f4febff74eb671