linux-user: Handle arches with llseek instead of _llseek

linux-user: Handle arches with llseek instead of _llseek

Recently merged kernel ports (such as OpenRISC and Meta) have an llseek
system call instead of _llseek. This is handled for the host
architecture by defining __NR__llseek as __NR_llseek, but not for the
target architecture.

Handle it in the same way for these architectures, defining
TARGET_NR__llseek as TARGET_NR_llseek.

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Riku Voipio <riku.voipio@iki.fi>
Cc: Jia Liu <proljc@gmail.com>
Signed-off-by: Riku Voipio <riku.voipio@linaro.org>