Moved RHASH_LEV_MASK and turned into a macro

Get rid of "ISO C restricts enumerator values to range of 'int'"
error.

hash.c

@@ -1317,10 +1317,11 @@ iter_lev_in_ivar_set(VALUE hash, int lev)
     rb_ivar_set_internal(hash, rb_intern("hash_iter_lev"), INT2FIX(lev));
 }
 
+#define RHASH_LEV_MASK ((VALUE)RHASH_LEV_MAX << RHASH_LEV_SHIFT)
 static int
 iter_lev_in_flags(VALUE hash)
 {
-    unsigned int u = (unsigned int)(RBASIC(hash)->flags & (unsigned int)RHASH_LEV_MASK) >> RHASH_LEV_SHIFT;
+    unsigned int u = (unsigned int)((RBASIC(hash)->flags >> RHASH_LEV_SHIFT) & RHASH_LEV_MAX);
     return (int)u;
 }
 

internal.h

@@ -827,8 +827,6 @@ enum ruby_rhash_flags {
     RHASH_TRANSIENT_FLAG = FL_USER12,                                    /* FL 12 */
 #endif
 
-    RHASH_LEV_MASK = (FL_USER13 | FL_USER14 | FL_USER15 |                /* FL 13..19 */
-                      FL_USER16 | FL_USER17 | FL_USER18 | FL_USER19),
     RHASH_LEV_SHIFT = (FL_USHIFT + 13),
     RHASH_LEV_MAX = 127, /* 7 bits */