avcodec/hevc: make *ps_id unsigned

Fixes integer overflow
Fixes out of array accesses
Fixes 2f65e7dbd02a12f426a423bd7bf880b4-signal_sigsegv_127c952_2793_cov_2517424539_RPLM_A_qualcomm_4.bit
Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/hevc.h

@@ -380,7 +380,7 @@ typedef struct ScalingList {
 } ScalingList;
 
 typedef struct HEVCSPS {
-    int vps_id;
+    unsigned vps_id;
     int chroma_format_idc;
     uint8_t separate_colour_plane_flag;
 
@@ -461,7 +461,7 @@ typedef struct HEVCSPS {
 } HEVCSPS;
 
 typedef struct HEVCPPS {
-    int sps_id; ///< seq_parameter_set_id
+    unsigned sps_id; ///< seq_parameter_set_id
 
     uint8_t sign_data_hiding_flag;