liblzma: Silence a warning from Coverity static analysis

It is logical why it cannot know for sure that the value has
to be at most 4 if it is less than 16.

The x86 filter is based on a very old LZMA SDK version. Newer
ones have quite a different implementation for the same filter.

Thanks to Sam James.

src/liblzma/simple/x86.c

@@ -26,11 +26,10 @@ static size_t
 x86_code(void *simple_ptr, uint32_t now_pos, bool is_encoder,
 		uint8_t *buffer, size_t size)
 {
-	static const bool MASK_TO_ALLOWED_STATUS[8]
-		= { true, true, true, false, true, false, false, false };
+	static const bool MASK_TO_ALLOWED_STATUS[5]
+			= { true, true, true, false, true };
 
-	static const uint32_t MASK_TO_BIT_NUMBER[8]
-			= { 0, 1, 2, 2, 3, 3, 3, 3 };
+	static const uint32_t MASK_TO_BIT_NUMBER[5] = { 0, 1, 2, 2, 3 };
 
 	lzma_simple_x86 *simple = simple_ptr;
 	uint32_t prev_mask = simple->prev_mask;
@@ -67,9 +66,8 @@ x86_code(void *simple_ptr, uint32_t now_pos, bool is_encoder,
 
 		b = buffer[buffer_pos + 4];
 
-		if (Test86MSByte(b)
-			&& MASK_TO_ALLOWED_STATUS[(prev_mask >> 1) & 0x7]
-				&& (prev_mask >> 1) < 0x10) {
+		if (Test86MSByte(b) && (prev_mask >> 1) <= 4
+			&& MASK_TO_ALLOWED_STATUS[(prev_mask >> 1)]) {
 
 			uint32_t src = ((uint32_t)(b) << 24)
 				| ((uint32_t)(buffer[buffer_pos + 3]) << 16)