Very few PAD[HA]Vs are "LVALUE": branch predictor hints

In a nutshell, very few PADHV and PADAV OPs are executed that have
the OPpLVAL_INTRO flag set. To wit, "my %h" does whereas "$h{foo}" and
similar (also "$h{foo} = 1") do not. Also, traditional lexicals greatly
outnumber state variables, so pessimize "state" slightly.

This was determined with a nifty new trick. With a Perl compiled with
-DPERL_TRACE_OPS, we get a summary of all executed op counts by type at
the end of the program execution. The above was figured out (naively) by
adding the following:

--- a/dump.c
+++ b/dump.c
@@ -2215,6 +2215,8 @@ Perl_runops_debug(pTHX)
     do {
 #ifdef PERL_TRACE_OPS
         ++PL_op_exec_cnt[PL_op->op_type];
+        if (PL_op->op_type == OP_PADHV && PL_op->op_private & OPpLVAL_INTRO)
+            ++PL_op_exec_cnt[OP_max+1];
 #endif
        if (PL_debug) {
            if (PL_watchaddr && (*PL_watchaddr != PL_watchok))

Which adds a special case (OP_max+1) to the OP report. Dividing that
count by the total PADHV count gives a diminishingly small percentage.