y2038: nptl: Provide __futex_clock_wait_bitset64 to support 64 bit bitset

The commit:
"y2038: nptl: Convert pthread_mutex_{clock|timed}lock to support 64 bit"
SHA1: 29e9874a

introduced support for 64 bit timeouts. Unfortunately, it was missing the
code for bitset - i.e. lll_futex_clock_wait_bitset C preprocessor macro
was used. As a result the 64 bit struct __timespec64 was coerced to 32
bit struct timespec and regression visible as timeout was observed
(nptl/tst-robust10 on s390).

Reported-by: Stefan Liebler <stli@linux.ibm.com>
Tested-by: Stefan Liebler <stli@linux.ibm.com>