[platform lib][osx][posix] missed declarations

klib/src/platform/osx/posix.def

@@ -13,7 +13,7 @@ headers = alloca.h ar.h assert.h complex.h dirent.h dlfcn.h err.h errno.h fcntl.
     sys/syslimits.h sys/time.h sys/times.h sys/wait.h
 
 compilerOpts = -D_XOPEN_SOURCE
-linkerOpts = -ldl
+linkerOpts = -ldl -lresolv
 
 ---
 // cinterop -def klib/src/platform/osx/posix.def -o platform.posix.klib
@@ -27,3 +27,19 @@ static int posix_errno() {
 static int posix_h_errno() {
     return h_errno;
 }
+
+static short posix_htons(short x) {
+	return htons(x);
+}
+
+static void posix_FD_ZERO(fd_set *set) {
+	FD_ZERO(set);
+}
+
+static void posix_FD_SET(int bit, fd_set *set) {
+	FD_SET(bit, set);
+}
+
+static int posix_FD_ISSET(int bit, fd_set *set) {
+	return FD_ISSET(bit, set);
+}