profiling of btf_dump

[Jose E. Marchesi]

btf_dump is slow.  Below is a PVM profiling of the execution of
`btf_dump (btf)' using your data.

I think mktyi (which is an instruction that creates an integer type) can
be optimized for the common case: we can pre-allocate and use type
values for all the signed and unsigned integer types in the range
1..64.  This actually covers now not just the common case, but all the
cases, until we support bigger integers with the GMP integration.

(poke) btf_dump (btf)
[1] int 'unsigned char'(0x00000001U#B) size=0x00000001U#B offset=0x00UB#b 
bits=0x08UB#b CHAR 
[2] int 'short unsigned int'(0x0000000fU#B) size=0x00000002U#B offset=0x00UB#b 
bits=0x10UB#b 
...
(poke) .vm profile show
mktyi        3719424    1.153us  19.9%
mko          2772695    1.435us  18.4%
mktysct      1351892    2.633us  16.5%
duc           360193    4.803us   8.0%
mktyo         963971  995.881ns   4.4%
mka            94305    9.862us   4.3%
mksct         530583    1.696us   4.2%
sublu        6973625  114.718ns   3.7%
regvar       6300039  119.047ns   3.5%
siz          2167311  332.209ns   3.3%
ains          223119    2.555us   2.6%
addlu        4475571   82.671ns   1.7%
peekdiu       591954  557.476ns   1.5%
mktya         325509  890.912ns   1.3%
pushvar     16233086   10.472ns   0.8%
pushe        1769727   90.409ns   0.7%
pushf         605697  198.119ns   0.6%
peeks          38049    2.891us   0.5%
swap        15731048    6.357ns   0.5%
push        35534470    2.533ns   0.4%
fromr        6897003    8.699ns   0.3%
sref          260212  230.581ns   0.3%
nip2        11584320    2.590ns   0.1%
tor          6897003    4.350ns   0.1%
nip          6716735    4.466ns   0.1%
pope         1633264   18.368ns   0.1%
lutoiu       1619600   18.523ns   0.1%
bsriu        1619458   18.525ns   0.1%
pec          1003116   29.907ns   0.1%
msets         936860   32.022ns   0.1%
raise         136058  220.494ns   0.1%
drop         6931908    2.885ns   0.1%
quake        5833066    3.429ns   0.1%
rot          2809243    7.119ns   0.1%
iutoiu       1774552   11.270ns   0.1%
ba           1150812   17.379ns   0.1%
prolog        670763   29.817ns   0.1%
msetw         624888   32.006ns   0.1%
dup          5092498    1.964ns   0.0%
popvar       4332460    2.308ns   0.0%
nrot         4004467    2.497ns   0.0%
over         3422410    2.922ns   0.0%
call          670763   14.908ns   0.0%
popf          601132   16.635ns   0.0%
map           598909   16.697ns   0.0%
msetm         598909   16.697ns   0.0%
mgets         260958   38.320ns   0.0%
mgetw         260958   38.320ns   0.0%
eqiu          155165   64.448ns   0.0%
peekdi         23023  434.348ns   0.0%
bzi          2541676 
msetios       936860 
return        670731 
drop2         649786 
mgetm         521916 
bnn           402480 
atr           337951 
gtlu          292044 
bnzi          283382 
mm            261588 
mgeto         261087 
mgetios       260958 
mgetsel       260958 
mgetsiz       260958 
bn            251273 
itoiu         148772 
sync          119336 
drop3          94325 
sel            93625 
eqi            87668 
aref           87476 
or             87272 
iutolu         69482 
bnzlu          68326 
mseto          68326 
msetsel        68326 
msetsiz        68326 
not            64727 
iutoi          39675 
ogetm           6126 
note            3699 
popend          3159 
ogetu           2087 
divlu           1955 
mullu           1955 
prints          1509 
mktys            831 
eqlu             792 
addiu            702 
printiu          321 
begsc            264 
endsc            264 
popod            264 
popom            264 
pushtopvar       264 
bzlu             132 
pushob           132 
pushod           132 
pushom           132 
pushios          129 
bziu              32 
printi            13 
revn              11 
asettb             8 
canary             1 
exit               1 
popr               1