9pfuse: Disable glibc workaround for O_LARGEFILE on ARM

9pfuse fails on ARM when O_LARGEFILE is supported.
glibc does define O_LARGEFILE properly on ARM,
and the value is different than what that this workaround suggests,
causing it to wrongly detect bad flags.

Change-Id: I02b0cc222ca7785c4b1739c3df3caa17cf7bc265
Reviewed-on: https://plan9port-review.googlesource.com/1094
Reviewed-by: Russ Cox <rsc@swtch.com>