clang complains:
> clang -g -O2 -Wall -Werror -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=0  -iquote ../lib/arch/x86/include -I../lib   vdso01.c ../lib/libzdtmtst.a ../lib/libzdtmtst.a -lrt -o vdso01
> vdso01.c:305:6: error: absolute value function 'abs' given an argument of type 'long' but has parameter of type 'int' which may cause truncation of value
>       [-Werror,-Wabsolute-value]
>         if (abs(ts1.tv_sec - ts2.tv_sec) > TIME_DELTA_SEC) {
>             ^
> vdso01.c:305:6: note: use function 'labs' instead

Let's use labs() indeed.
Signed-off-by: Kir Kolyshkin <kir@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>