Preprocessor # should be the top of line.

src/string.c

@@ -2275,7 +2275,7 @@ mrb_cstr_to_dbl(mrb_state *mrb, const char * p, int badcheck)
   char *end;
   double d;
 #if !defined(DBL_DIG)
-  #define DBL_DIG 16
+# define DBL_DIG 16
 #endif
 
   enum {max_width = 20};