Bug 14553 reports that sys/types.h defines loff_t unconditionally,
despite it not being part of any supported standard. This is
permitted by the POSIX *_t reservation, but as a
quality-of-implementation issue it's still best not to define it
except for __USE_MISC. This patch conditions the definition
accordingly, updating a macro in sysdeps/unix/sysv/linux/sys/quota.h
to use __loff_t so it still works even if __USE_MISC is not defined.
codesearch.debian.net suggests there are quite a lot of loff_t uses
outside glibc, but it might well make sense to change all (few) uses
of loff_t or __loff_t inside glibc to use off64_t or __off64_t
instead, leaving only the definitions, treating this name as
obsolescent.
Tested for x86_64.
[BZ #14553]
* posix/sys/types.h (loff_t): Only define for [__USE_MISC].
* sysdeps/unix/sysv/linux/sys/quota.h (dqoff): Use __loff_t
instead of loff_t.