fallocate/fallocate02.c: fix compilation error on RHEL5.10

Add #define _GNU_SOURCE in order to have LLONG_MAX defined on RHEL5.10.

Signed-off-by: Xiaoguang Wang <wangxg.fnst@cn.fujitsu.com>
m4/ltp-fallocate.m4: add configure check for fallocate(2)

ltp-fallocate.m4: create a configure check for fallocate() syscall and
define the wrapper only when it's not available.

Signed-off-by: Xiaoguang Wang <wangxg.fnst@cn.fujitsu.com>
fallocate/fallocate02.c: delete a invalid test item

fallocate02.c: delete this test item "{&fdw, FNAMEW, DEFAULT_TEST_MODE,
BLOCKS_WRITTEN-OFFSET, 1, 0}". Fallocate02 is to test various error
conditions for fallocate() syscall, usually these error conditions
can be checked in vfs layer. Here this test item, which the expected
return value is 0, is dependent on whether the underlying file systems
implement fallocate. So here we choose to remove it, or may specify a
block device, which contains a ext4 file system.

Signed-off-by: Xiaoguang Wang <wangxg.fnst@cn.fujitsu.com>