Fixed kmsdrm using standard C functions instead of SDL functions

src/video/kmsdrm/SDL_kmsdrmvideo.c

@@ -548,7 +548,7 @@ KMSDRM_CrtcGetPropId(uint32_t drm_fd,
         if (!drm_prop)
             continue;
 
-        if (strcmp(drm_prop->name, name) == 0)
+        if (SDL_strcmp(drm_prop->name, name) == 0)
             prop_id = drm_prop->prop_id;
 
         KMSDRM_drmModeFreeProperty(drm_prop);
@@ -599,7 +599,7 @@ KMSDRM_ConnectorCheckVrrCapable(uint32_t drm_fd,
         if (!drm_prop)
             continue;
 
-        if (strcasecmp(drm_prop->name, name) == 0) {
+        if (SDL_strcasecmp(drm_prop->name, name) == 0) {
             prop_value = props->prop_values[i];
             found = SDL_TRUE;
         }