libyang REFACTOR use size-specific int types instead of generic types (#1177)

Align parameters' types with the values in (internal) structures.
diff --git a/src/parser_stmt.c b/src/parser_stmt.c
index c9b5809..af0feee 100644
--- a/src/parser_stmt.c
+++ b/src/parser_stmt.c
@@ -32,8 +32,8 @@
 static LY_ERR
 lysp_stmt_validate_value(struct lys_parser_ctx *ctx, enum yang_arg val_type, const char *val)
 {
-    int prefix = 0, first = 1;
-    unsigned int c;
+    uint8_t prefix = 0, first = 1;
+    uint32_t c;
     size_t utf8_char_len;
 
     while (*val) {