LibC: Implement gethostbyname() by talking to the DNSLookupServer.

We now talk to the lookup server over a local socket and it does the lookup
on our behalf. Including some retry logic, which is nice, because it seems
like DNS requests disappear in the ether pretty damn often where I am.

Userland/host.cpp

@@ -0,0 +1,24 @@
+#include <netdb.h>
+#include <arpa/inet.h>
+#include <netinet/in.h>
+#include <stdio.h>
+
+int main(int argc, char** argv)
+{
+    if (argc < 2) {
+        printf("usage: host <hostname>\n");
+        return 0;
+    }
+
+    auto* hostent = gethostbyname(argv[1]);
+    if (!hostent) {
+        printf("Lookup failed for '%s'\n", argv[1]);
+        return 1;
+    }
+
+    char buffer[32];
+    const char* ip_str = inet_ntop(AF_INET, hostent->h_addr_list[0], buffer, sizeof(buffer));
+
+    printf("%s is %s\n", argv[1], ip_str);
+    return 0;
+}