Fix <resolv.h> and <netinet/tcp.h> so dnscap builds.

Some guy on the internet complained that dnscap doesn't build out of the box.
Now it does.

Bug: http://b/27839637
Change-Id: I8c4f22d3c3f8885a6fe06029d89ef68a15931027
diff --git a/libc/include/netinet/tcp.h b/libc/include/netinet/tcp.h
index e95cc09..147f6f7 100644
--- a/libc/include/netinet/tcp.h
+++ b/libc/include/netinet/tcp.h
@@ -30,11 +30,56 @@
 #define _NETINET_TCP_H
 
 #include <sys/cdefs.h>
+#include <stdint.h>
 
+#define tcphdr __kernel_tcphdr
 #include <linux/tcp.h>
+#undef tcphdr
 
 __BEGIN_DECLS
 
+struct tcphdr {
+  __extension__ union {
+    struct {
+      uint16_t th_sport;
+      uint16_t th_dport;
+      uint32_t th_seq;
+      uint32_t th_ack;
+      uint8_t th_x2:4;
+      uint8_t th_off:4;
+      uint8_t th_flags;
+      uint16_t th_win;
+      uint16_t th_sum;
+      uint16_t th_urp;
+    };
+    struct {
+      uint16_t source;
+      uint16_t dest;
+      uint32_t seq;
+      uint32_t ack_seq;
+      uint16_t res1:4;
+      uint16_t doff:4;
+      uint16_t fin:1;
+      uint16_t syn:1;
+      uint16_t rst:1;
+      uint16_t psh:1;
+      uint16_t ack:1;
+      uint16_t urg:1;
+      uint16_t res2:2;
+      uint16_t window;
+      uint16_t check;
+      uint16_t urg_ptr;
+    };
+  };
+};
+
+#define TH_FIN 0x01
+#define TH_SYN 0x02
+#define TH_RST 0x04
+#define TH_PUSH 0x08
+#define TH_ACK 0x10
+#define TH_URG 0x20
+
 enum {
   TCP_ESTABLISHED = 1,
   TCP_SYN_SENT,
diff --git a/libc/include/resolv.h b/libc/include/resolv.h
index b10aaf4..aca3552 100644
--- a/libc/include/resolv.h
+++ b/libc/include/resolv.h
@@ -25,6 +25,7 @@
  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  */
+
 #ifndef _RESOLV_H_
 #define _RESOLV_H_
 
@@ -40,13 +41,24 @@
 #pragma GCC visibility push(default)
 
 #define b64_ntop __b64_ntop
+int b64_ntop(u_char const*, size_t, char*, size_t);
 #define b64_pton __b64_pton
-extern int b64_ntop(u_char const*, size_t, char*, size_t);
-extern int b64_pton(char const*, u_char*, size_t);
+int b64_pton(char const*, u_char*, size_t);
 
 #define dn_comp __dn_comp
-extern int dn_comp(const char*, u_char*, int, u_char**, u_char**);
-extern int dn_expand(const u_char*, const u_char*, const u_char*, char*, int);
+int dn_comp(const char*, u_char*, int, u_char**, u_char**);
+
+int dn_expand(const u_char*, const u_char*, const u_char*, char*, int);
+
+#define p_class __p_class
+const char* p_class(int);
+#define p_type __p_type
+const char* p_type(int);
+
+int res_init(void);
+int res_mkquery(int, const char*, int, int, const u_char*, int, const u_char*, u_char*, int);
+int res_query(const char*, int, int, u_char*, int);
+int res_search(const char*, int, int, u_char*, int);
 
 #pragma GCC visibility pop
 __END_DECLS