Stricter handling of erroneous input when converting CP5022{0,1,2} text encoding

Don't allow escape sequences to start in the middle of a multibyte character.
Also, don't silently pass through illegal bytes which appear where the 2nd
byte of a multibyte character should be.

Author: alexdowad

ext/mbstring/libmbfl/filters/mbfilter_cp5022x.c

@@ -273,20 +273,12 @@ mbfl_filt_conv_jis_ms_wchar(int c, mbfl_convert_filter *filter)
 					w = 0;
 				}
 				if (w <= 0) {
-					w = (c1 << 8) | c;
-					w &= MBFL_WCSPLANE_MASK;
-					w |= MBFL_WCSPLANE_JIS0212;
+					w = (c1 << 8) | c | MBFL_WCSPLANE_JIS0212;
 				}
 			}
 			CK((*filter->output_function)(w, filter->data));
-		} else if (c == 0x1b) {
-			filter->status += 2;
-		} else if ((c >= 0 && c < 0x21) || c == 0x7f) {		/* CTLs */
-			CK((*filter->output_function)(c, filter->data));
 		} else {
-			w = (c1 << 8) | c;
-			w &= MBFL_WCSGROUP_MASK;
-			w |= MBFL_WCSGROUP_THROUGH;
+			w = (c1 << 8) | c | MBFL_WCSGROUP_THROUGH;
 			CK((*filter->output_function)(w, filter->data));
 		}
 		break;