syscalls/fallocate02: Fix failure on 32bit hardware

On 32 bit hardware where off_t is 4 bytes long the LLONG_MAX value
overflows to negative numbers and fallocate() returns EINVAL instead of
EFBIG.

The kernel do_allocate() syscall code uses loff_t for both offset and
len so there is no way to overflow it with 32 bit numbers.

So we enable these two cases only on 64 bit hardware or if
_FILE_OFFSET_BITS is set to 64.

Signed-off-by: Cyril Hrubis <chrubis@suse.cz>