* include/freetype/ftlogging.h: New header file.
* include/freetype/internal/ftdebug.h [FT_LOGGING]: Include
`ftlogging.h`.
* src/base/ftdebug.c (ft_custom_trace_level): New variable.
(ft_debug_init): Update to support change of levels of tracing
components of FreeType at run-time.
(FT_Trace_Set_Level): New function to change the levels of tracing
components at run-time.
(FT_Trace_Set_Default_Level): New function to reset the levels of
tracing components back to default.
Priyesh Kumar