raise i386's datasize for 'daemon' class so that relinking libc at boot

raise i386's datasize for 'daemon' class so that relinking libc at boot
doesn't fail - new clang is even greedier than the old one.

I picked the value 1500M out of the air, it works for me but could perhaps
be finessed downwards a bit.

(I'm also using 1500M for make build / mkr+mkrx on i386; make -j8 build
is no longer a good idea on i386 ;)