statfs: bugfix statfs02 fstatfs02 failed in ltp-testsuite
In the test-case of statfs from ltp-testsuite, it pass -1 to 2th
argument. eg: fstatfs(fd , -1)
When uclibc-ng parse the buf32 to buf will cause illegal address
access, the kernel will signal the process with SIGSEGV.
If we pass the -1 directly to the syscall of statfs/fstatfs, kernel
use copy_to_user() to prevent the signal of SIGSEGV and just return
EINVAL.
This is the ltp-testsuite expect.
Signed-off-by: Guo Ren <ren_guo@c-sky.com>