This turns EM `con 5000000000I8` into assembly `.data8 5000000000` for
machines i386, i80, i86, m68020, powerpc, vc4. These are the only ncg
machines in our build.
i80 and i86 get con_mult(sz) for sz == 4 and sz == 8. The other
machines only get sz == 8, because they have 4-byte words, and ncg
only calls con_mult(sz) when sz is greater than the word size. The
tab "\t" after .data4 or .data8 is like the tabs in the con_*() macros
of mach/*/ncg/mach.h.
i86 now uses .data4, like i80. Also, i86 and i386 now use the numeric
string without converting it to an integer and back to a string.
gcc gave an error because the `char *` parameter doesn't match the
`const char *` in the prototype of regsave(). clang didn't give an
error. I added the prototype in commit 5301cce.
This breaks all machines because the declared return type void
disagrees with the implicit return type int (when I compile mach.c
with clang). Unbreak i386, i80, i86, m68020, powerpc, vc4 by adding
the return types to mach.c. We don't build any other machines; they
are broken since commit a46ee91 (May 19, 2013) declared void prolog()
and commit fd91851 (Nov 10, 2016) declared void mes(), with both
declarations in mach/proto/ncg/fillem.c.
Also fix mach/vc4/ncg/mach.c where type full is long, so fprintf()
must use "%ld" not "%d" to print full nlocals.
