Fix hard-to-rigger locking bug in vsyslog():

Fix hard-to-rigger locking bug in vsyslog():
SIGPIPE handler was attempting to re-acquire an already taken lock.
While at it, stop checking for sigaction failure which is not possible here.
Sizes:

    text           data     bss     dec     hex filename
-   1123             13       2    1138     472 libc/misc/syslog/syslog.o
+   1112             13       2    1127     467 libc/misc/syslog/syslog.o

Run tested.