configure: Simplify alternate .text segment

configure: Simplify alternate .text segment

For bsd-user and linux-user emulation modes QEMU needs to be linked at an
alternate .text segment address, so that it's out of the way of the guest
executable.  Instead of including modified linker scripts for each arch,
just set the address with -Ttext-segment if supported, or by using sed to
edit the default linker script.

Cc: Ed Maste <emaste@freebsd.org>
Signed-off-by: Richard Henderson <rth@twiddle.net>
Acked-by: Ed Maste <emaste@freebsd.org>
Signed-off-by: Ed Maste <emaste@freebsd.org>
Message-id: 1371867016-7660-1-git-send-email-rth@twiddle.net
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>