dump.h: parenthesize negative errnos

include/mruby/dump.h

@@ -28,14 +28,14 @@ mrb_irep *mrb_read_irep(mrb_state*, const uint8_t*);
  * NOTE: MRB_DUMP_GENERAL_FAILURE is caused by
  * unspecified issues like malloc failed.
  */
-#define MRB_DUMP_OK                   0
-#define MRB_DUMP_GENERAL_FAILURE      -1
-#define MRB_DUMP_WRITE_FAULT          -2
-#define MRB_DUMP_READ_FAULT           -3
-#define MRB_DUMP_CRC_ERROR            -4
-#define MRB_DUMP_INVALID_FILE_HEADER  -5
-#define MRB_DUMP_INVALID_IREP         -6
-#define MRB_DUMP_INVALID_ARGUMENT     -7
+#define MRB_DUMP_OK                     0
+#define MRB_DUMP_GENERAL_FAILURE      (-1)
+#define MRB_DUMP_WRITE_FAULT          (-2)
+#define MRB_DUMP_READ_FAULT           (-3)
+#define MRB_DUMP_CRC_ERROR            (-4)
+#define MRB_DUMP_INVALID_FILE_HEADER  (-5)
+#define MRB_DUMP_INVALID_IREP         (-6)
+#define MRB_DUMP_INVALID_ARGUMENT     (-7)
 
 /* null symbol length */
 #define MRB_DUMP_NULL_SYM_LEN         0xFFFF