[FIX] chore: remove two dead includes flagged by clangd (#2329)

ccx_common_char_encoding.h in ccx_decoders_common.c is unused —
the functions it declares moved to ccx_encoders_common.c after a
2014 refactor and the include was never cleaned up.

ccx_demuxer_mxf.h in general_loop.c is also unused — general_loop.c
handles MXF via ccx_mxf_getmoredata, which is already declared in
lib_ccx.h (included separately). This header appears to have been
added by reflex alongside MXF support in 2017 without ever being
needed.

A third flagged include, ffmpeg_intgr.h in general_loop.c, was
investigated and left untouched — it's a genuine dependency under

Closes #2328

src/lib_ccx/ccx_decoders_common.c

@@ -3,7 +3,6 @@ made to reuse, not duplicate, as many functions as possible */
 
 #include "ccx_decoders_common.h"
 #include "ccx_common_structs.h"
-#include "ccx_common_char_encoding.h"
 #include "ccx_common_constants.h"
 #include "ccx_common_timing.h"
 #include "ccx_common_common.h"

src/lib_ccx/general_loop.c

@@ -17,7 +17,6 @@
 #include "ffmpeg_intgr.h"
 #include "ccx_gxf.h"
 #include "dvd_subtitle_decoder.h"
-#include "ccx_demuxer_mxf.h"
 #include "ccx_dtvcc.h"
 
 int end_of_file = 0; // End of file?