recv(),send(): Directly call interposing entry instead of going throu…

…gh PLT.

recv() and send()'s calls to recvfrom() and sendto() are much like
waitpid()'s call to wait4(), and likewise need not allow PLT interposing on
the called function.

lib/libc/net/recv.c

@@ -35,6 +35,7 @@ __FBSDID("$FreeBSD$");
 
 #include <sys/types.h>
 #include <sys/socket.h>
+#include "libc_private.h"
 
 #include <stddef.h>
 
@@ -48,5 +49,8 @@ recv(s, buf, len, flags)
 	 * POSIX says recv() shall be a cancellation point, so call the
 	 * cancellation-enabled recvfrom() and not _recvfrom().
 	 */
-	return (recvfrom(s, buf, len, flags, NULL, 0));
+	return (((ssize_t (*)(int, void *, size_t, int,
+	    struct sockaddr *, socklen_t *))
+	    __libc_interposing[INTERPOS_recvfrom])(s, buf, len, flags,
+	   NULL, NULL));
 }

lib/libc/net/send.c

@@ -35,6 +35,7 @@ __FBSDID("$FreeBSD$");
 
 #include <sys/types.h>
 #include <sys/socket.h>
+#include "libc_private.h"
 
 #include <stddef.h>
 
@@ -48,5 +49,8 @@ send(s, msg, len, flags)
 	 * POSIX says send() shall be a cancellation point, so call the
 	 * cancellation-enabled sendto() and not _sendto().
 	 */
-	return (sendto(s, msg, len, flags, NULL, 0));
+	return (((ssize_t (*)(int, const void *, size_t, int,
+	    const struct sockaddr *, socklen_t))
+	    __libc_interposing[INTERPOS_sendto])(s, msg, len, flags,
+	    NULL, 0));
 }