The documentation for -fpic and -fPIC explicitly mentions some targets
where the difference matters, but not AArch64.  Specifying the GOT size
limit is not entirely correct as it can depend on the -mcmodel setting,
but probably better than leaving the impression that -fpic vs -fPIC does
not matter on AArch64.

ChangeLog:

2015-11-12  Szabolcs Nagy  <szabolcs.nagy@arm.com>

	* doc/invoke.texi (-fpic): Add the AArch64 limit.
	(-fPIC): Add AArch64.