Updated quirc to v1.1 (2019); patched to remove compiler warnings

source/quirc/quirc.h

@@ -19,6 +19,10 @@
 
 #include <stdint.h>
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 struct quirc;
 
 /* Obtain the library version string. */
@@ -117,7 +121,7 @@ struct quirc_code {
 	 * is a bitmask giving the actual values of cells. If the cell
 	 * at (x, y) is black, then the following bit is set:
 	 *
-	 *     cell_bitmap[i << 3] & (1 << (i & 7))
+	 *     cell_bitmap[i >> 3] & (1 << (i & 7))
 	 *
 	 * where i = (y * size) + x.
 	 */
@@ -162,4 +166,8 @@ void quirc_extract(const struct quirc *q, int index,
 quirc_decode_error_t quirc_decode(const struct quirc_code *code,
 				  struct quirc_data *data);
 
+#ifdef __cplusplus
+}
+#endif
+
 #endif