only add the trailing nop if the catch table is not break / next / redo

[tenderlove]

We don't need nop padding when the catch tables are only for break /
next / redo, so lets avoid them. This eliminates nop padding in
many lambdas.

I think this is a better alternative to #4040.

Here are the instructions used for RailsBench on master:

Text version:

10               setinstancevariable  4332095
97                     getlocal_WC_1  5175882
17                            putnil  6911093
83                          opt_aref  8455003
19                         putobject  9321480
35                               pop  9635247
98                     setlocal_WC_0 11036016
62                          branchif 11088913
9                getinstancevariable 12011517
36                               dup 12020746
65                opt_getinlinecache 13121324
63                      branchunless 13441822
1                                nop 15066779
18                           putself 24045912
59                             leave 34046308
51            opt_send_without_block 45677897
96                     getlocal_WC_0 58353340

Here are the instructions used on this branch:

97                     getlocal_WC_1  5175882
1                                nop  6869821
17                            putnil  6911093
83                          opt_aref  8455003
19                         putobject  9321480
35                               pop  9635251
98                     setlocal_WC_0 11036016
62                          branchif 11087301
9                getinstancevariable 12009905
36                               dup 12019146
65                opt_getinlinecache 13121328
63                      branchunless 13441838
18                           putself 24045118
59                             leave 34043898
51            opt_send_without_block 45675507
96                     getlocal_WC_0 58352550

This patch eliminates about 8mil nop calls.

Here is the req / s graph:

It seems like there is some improvement, though it's not huge.

/cc @XrXr @jhawthorn