MySQL can't start: Symbol not found: _clock_gettime
I don't think it matters because the symbol doesn't exist where mysql expects it to:

$ nm -gU /usr/lib/libSystem.B.dylib
0000000000001a98 T R8289209$_close
0000000000001a9d T R8289209$_fork
0000000000001aa2 T R8289209$_fsync
0000000000001aa7 T R8289209$_getattrlist
0000000000001aac T R8289209$_getrlimit
0000000000001ab1 T R8289209$_getxattr
0000000000001ab6 T R8289209$_open
0000000000001abb T R8289209$_pthread_attr_destroy
0000000000001ac0 T R8289209$_pthread_attr_init
0000000000001ac5 T R8289209$_pthread_attr_setdetachstate
0000000000001aca T R8289209$_pthread_create
0000000000001acf T R8289209$_pthread_mutex_lock
0000000000001ad4 T R8289209$_pthread_mutex_unlock
0000000000001ad9 T R8289209$_pthread_self
0000000000001ade T R8289209$_ptrace
0000000000001ae3 T R8289209$_read
0000000000001ae8 T R8289209$_setattrlist
0000000000001aed T R8289209$_setrlimit
0000000000001af2 T R8289209$_sigaction
0000000000001af7 T R8289209$_stat
0000000000001afc T R8289209$_sysctl
0000000000001b01 T R8289209$_time
0000000000001b06 T R8289209$_unlink
0000000000001b0b T R8289209$_write
0000000000001f98 S ___System_BVersionNumber
0000000000001f60 S ___System_BVersionString
00000000000022b8 S ___crashreporter_info__
0000000000001b10 T _libSystem_atfork_child
0000000000001a7a T _libSystem_atfork_parent
0000000000001a5c T _libSystem_atfork_prepare
00000000000022b0 D _mach_init_routine


John