[msan] Remove a stale fixme (NFC).
It was fixed in 312576.
@@ -995,8 +995,6 @@ static void read_sigaction(const __sanitizer_sigaction *act) {
INTERCEPTOR(int, sigaction, int signo, const __sanitizer_sigaction *act,
__sanitizer_sigaction *oldact) {
ENSURE_MSAN_INITED();
- // FIXME: check that *act is unpoisoned.
- // That requires intercepting all of sigemptyset, sigfillset, etc.
if (act) read_sigaction(act);
int res;
if (flags()->wrap_signals) {
