Merge branch 'ew/daemon-socket-keepalive' into maint

Recent update to "git daemon" tries to enable the socket-level
KEEPALIVE, but when it is spawned via inetd, the standard input
file descriptor may not necessarily be connected to a socket.
Suppress an ENOTSOCK error from setsockopt().

* ew/daemon-socket-keepalive:
  Windows: add missing definition of ENOTSOCK
  daemon: ignore ENOTSOCK from setsockopt

compat/mingw.h

@@ -73,6 +73,9 @@ typedef int pid_t;
 #ifndef ECONNABORTED
 #define ECONNABORTED WSAECONNABORTED
 #endif
+#ifndef ENOTSOCK
+#define ENOTSOCK WSAENOTSOCK
+#endif
 
 struct passwd {
 	char *pw_name;

daemon.c

@@ -673,9 +673,11 @@ static void set_keep_alive(int sockfd)
 {
 	int ka = 1;
 
-	if (setsockopt(sockfd, SOL_SOCKET, SO_KEEPALIVE, &ka, sizeof(ka)) < 0)
-		logerror("unable to set SO_KEEPALIVE on socket: %s",
-			strerror(errno));
+	if (setsockopt(sockfd, SOL_SOCKET, SO_KEEPALIVE, &ka, sizeof(ka)) < 0) {
+		if (errno != ENOTSOCK)
+			logerror("unable to set SO_KEEPALIVE on socket: %s",
+				strerror(errno));
+	}
 }
 
 static int execute(void)