Linux is 128 bytes so directly inline the functions

internal/fakecgo/go_libinit.go

@@ -50,17 +50,17 @@ func _cgo_try_pthread_create(thread *pthread_t, attr *pthread_attr_t, pfn unsafe
 	var err int
 
 	for tries = 0; tries < 20; tries++ {
-		err = int(pthread_create(thread, attr, pfn, unsafe.Pointer(arg)))
+		err = int(call5(pthread_createABI0, uintptr(unsafe.Pointer(thread)), uintptr(unsafe.Pointer(attr)), uintptr(pfn), uintptr(unsafe.Pointer(arg)), 0))
 		if err == 0 {
-			pthread_detach(*thread)
+			call5(pthread_detachABI0, uintptr(*thread), 0, 0, 0, 0)
 			return 0
 		}
 		if err != int(syscall.EAGAIN) {
 			return err
 		}
 		ts.Sec = 0
 		ts.Nsec = (tries + 1) * 1000 * 1000 // Milliseconds.
-		nanosleep(&ts, nil)
+		call5(nanosleepABI0, uintptr(unsafe.Pointer(&ts)), 0, 0, 0, 0)
 	}
 	return int(syscall.EAGAIN)
 }

internal/fakecgo/libcgo.go

@@ -8,9 +8,10 @@ package fakecgo
 type (
 	size_t uintptr
 	// Sources:
-	// Darwin - https://github.com/apple/darwin-xnu/blob/2ff845c2e033bd0ff64b5b6aa6063a1f8f65aa32/bsd/sys/_types.h#L74
-	// FreeBSD - https://github.com/DoctorWkt/xv6-freebsd/blob/d2a294c2a984baed27676068b15ed9a29b06ab6f/include/signal.h#L98C9-L98C21
-	sigset_t       [32]byte
+	// Darwin (32 bytes) - https://github.com/apple/darwin-xnu/blob/2ff845c2e033bd0ff64b5b6aa6063a1f8f65aa32/bsd/sys/_types.h#L74
+	// FreeBSD (32 bytes) - https://github.com/DoctorWkt/xv6-freebsd/blob/d2a294c2a984baed27676068b15ed9a29b06ab6f/include/signal.h#L98C9-L98C21
+	// Linux (128 bytes) - https://github.com/torvalds/linux/blob/ab75170520d4964f3acf8bb1f91d34cbc650688e/arch/x86/include/asm/signal.h#L25
+	sigset_t       [128]byte
 	pthread_attr_t [64]byte
 	pthread_t      int
 	pthread_key_t  uint64