[squash-me] PR review fix: be consistent with NULL

Author: ekotik

intrpvar.h

@@ -65,7 +65,7 @@ PERLVARI(I, hash_rand_bits_enabled, U8, 1) /* used to randomize hash stuff
 #endif
 PERLVARI(I, hash_rand_bits, UV, 0)      /* used to randomize hash stuff */
 #endif
-PERLVARI(I, strtab,	HV *, 0)		/* shared string table */
+PERLVARI(I, strtab,	HV *, NULL)		/* shared string table */
 /* prog counter for the currently executing OP_MULTIDEREF Used to signal
  * to S_find_uninit_var() where we are */
 PERLVAR(I, multideref_pc, UNOP_AUX_item *)