[squash-me] PR review fix: nullify PL_strtab in perl_destruct

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 *, NULL)		/* shared string table */
+PERLVARI(I, strtab,	HV *, 0)		/* 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 *)

perl.c

@@ -1389,6 +1389,7 @@ perl_destruct(pTHXx)
         HvTOTALKEYS(PL_strtab) = 0;
     }
     SvREFCNT_dec(PL_strtab);
+    PL_strtab = NULL;
 
 #ifdef USE_ITHREADS
     /* free the pointer tables used for cloning */