libyang FEATURE introduce and use new ly_bool type

To indicate simple flags or true/false return values, use a standalone
ly_bool type.

We do not use stdbool's bool type to avoid need to mimic all its
features on platforms that do not provide it. ly_bool is just a simple
rename for uint8_t and the reason to use it is only a better readability
of the meaning of the variables or function's return values.
diff --git a/src/parser.h b/src/parser.h
index 2c35f24..9375bef 100644
--- a/src/parser.h
+++ b/src/parser.h
@@ -167,7 +167,7 @@
  * @param[in] destroy Flag to free the input data buffer (for LY_IN_MEMORY) or to
  * close stream/file descriptor (for LY_IN_FD and LY_IN_FILE)
  */
-void ly_in_free(struct ly_in *in, uint8_t destroy);
+void ly_in_free(struct ly_in *in, ly_bool destroy);
 
 #ifdef __cplusplus
 }