Fix --indent 0 implicitly enabling compact-output

Now it will retain pretty-printing, just remove any indentation.

src/jv.h

@@ -223,7 +223,7 @@ enum jv_print_flags {
   JV_PRINT_SPACE2   = 1024,
 };
 #define JV_PRINT_INDENT_FLAGS(n) \
-    ((n) < 0 || (n) > 7 ? JV_PRINT_TAB | JV_PRINT_PRETTY : (n) == 0 ? 0 : (n) << 8 | JV_PRINT_PRETTY)
+    ((n) < 0 || (n) > 7 ? JV_PRINT_TAB | JV_PRINT_PRETTY : (n) == 0 ? JV_PRINT_PRETTY : (n) << 8 | JV_PRINT_PRETTY)
 void jv_dumpf(jv, FILE *f, int flags);
 void jv_dump(jv, int flags);
 void jv_show(jv, int flags);