Revert "parser: make duplicated functions an error (#8792)"

This reverts commit 21bf8fe14e.

vlib/net/unix/aasocket.c.v

@@ -43,3 +43,60 @@ mut:
 
 struct C.sockaddr_storage {
 }
+
+fn C.socket() int
+
+fn C.setsockopt() int
+
+fn C.htonl() int
+
+fn C.htons() int
+
+fn C.bind() int
+
+fn C.listen() int
+
+fn C.accept() int
+
+fn C.getaddrinfo() int
+
+fn C.connect() int
+
+fn C.send() int
+
+fn C.sendto() int
+
+fn C.recv() int
+
+fn C.recvfrom() int
+
+fn C.shutdown() int
+
+fn C.ntohs() int
+
+fn C.getpeername() int
+
+fn C.inet_ntop(af int, src voidptr, dst charptr, dst_size int) charptr
+
+fn C.WSAAddressToStringA() int
+
+fn C.getsockname() int
+
+// defined in builtin
+// fn C.read() int
+// fn C.close() int
+
+fn C.ioctlsocket() int
+
+fn C.fcntl() int
+
+fn C.@select() int
+
+fn C.FD_ZERO()
+
+fn C.FD_SET()
+
+fn C.FD_ISSET() bool
+
+[typedef]
+struct C.fd_set {}