Add __ulock_wait, __ulock_wait2, and __ulock_wake

This is an internal API, but it's also used in LLVM libc++ so I would
assume the interface should be pretty stable. See:
https://github.com/llvm/llvm-project/blob/release/18.x/libcxx/src/atomic.cpp#L68-L70

Author: aykevl

src/arm64/libSystem.s

@@ -85,6 +85,15 @@ ___svfscanf:
 .global ___swbuf
 ___swbuf:
 
+.global ___ulock_wait
+___ulock_wait:
+
+.global ___ulock_wait2
+___ulock_wait2:
+
+.global ___ulock_wake
+___ulock_wake:
+
 .global ___vsnprintf_chk
 ___vsnprintf_chk:
 

src/libSystem.h

@@ -19,3 +19,8 @@
 
 // These symbols must be declared manually.
 extern char **environ;
+
+// These symbols are internal and must therefore be declared manually.
+int __ulock_wait(uint32_t operation, void *addr, uint64_t value, uint32_t timeout_us);
+int __ulock_wait2(uint32_t operation, void *addr, uint64_t value, uint64_t timeout_ns, uint64_t value2);
+int __ulock_wake(uint32_t operation, void *addr, uint64_t wake_value);

src/x86_64/libSystem.s

@@ -85,6 +85,15 @@ ___svfscanf:
 .global ___swbuf
 ___swbuf:
 
+.global ___ulock_wait
+___ulock_wait:
+
+.global ___ulock_wait2
+___ulock_wait2:
+
+.global ___ulock_wake
+___ulock_wake:
+
 .global ___vsnprintf_chk
 ___vsnprintf_chk: