fix x86_64 lrintl asm, again
fix x86_64 lrintl asm, again

the underlying problem was not incorrect sign extension (fixed in the
previous commit to this file by nsz) but that code that treats "long"
as 32-bit was copied blindly from i386 to x86_64.

now lrintl is identical to llrintl on x86_64, as it should be.

chardi/musl,chardi/musl,chardi/musl