This shrinks a binary that just does an http.ListenAndServe by about
90kb due to using less code for the static array.

 syms
 delta   name                                                old-size  new-size  pct-difference
-54206   vendor/golang_org/x/net/http2/hpack.newStaticTable  55233     1027      -98.14%
-4744    runtime.pclntab                                     1041055   1036311   -0.46%
-204     runtime.findfunctab                                 10675     10471     -1.91%
8        runtime.typelink                                    9852      9860      0.08%
41       runtime.gcbss                                       869       910       4.72%
11711    vendor/golang_org/x/net/http2/hpack.init            572       12283     2047.38%

 sections
 delta   name             old-size  new-size  pct-difference
-41888   .text            2185840   2143952   -1.92%
-37644   .rodata          842131    804487    -4.47%
-4744    .gopclntab       1041055   1036311   -0.46%
-3343    .debug_info      981995    978652    -0.34%
-2931    .debug_line      291295    288364    -1.01%
8        .typelink        9852      9860      0.08%
59       .debug_pubnames  81986     82045     0.07%
96       .symtab          186312    186408    0.05%
113      .debug_pubtypes  137500    137613    0.08%
128      .debug_frame     219140    219268    0.06%
220      .strtab          217109    217329    0.10%
2464     .bss             127752    130216    1.93%

Updates golang/go#6853

Change-Id: I3383e63300585539507b75faac1072264d8f37e7
Reviewed-on: https://go-review.googlesource.com/43090Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>