AC_SYS_LARGEFILE macro

[Andrej Borsenkow]

I was about to replace our custom check for LFS flags with AC_SYS_LARGEFILE
but found that it is no real replacement.

It checks only for specific option for IRIX and _FILE_OFFSET_BITS and
_LARGE_FILES macros. That is not enough; e.g. on our system:

address@hidden getconf LFS_CFLAGS
-D_FILE_OFFSET_BITS=64 -D_LONGLONG -Kll64

Additionally, if package is using ftello/fseeko it is expected to set
_LARGEFILE_SOURCE ... granted, it is independent of off_t size but still
related.

Add to that possibilty of special LDFLAGS that may be needed.

So, the question is - why AC_SYS_LARGEFILE does not use getconf that is the
sdtandard interface to obtain {C,LD}FLAGS needed to compile program with LFS
support? Nothing prevents explicit check for the above two macros if getconf
is unavailable or returns bogus values.

-andrej