chg: extract the logic of setting FD_CLOEXEC to a utility function

Setting FD_CLOEXEC is useful for other fds such like lockfd and sockdirfd,
move the logic from hgc_open to util.

contrib/chg/hgclient.c

@@ -418,11 +418,7 b' hgclient_t *hgc_open(const char *socknam'
 
 	/* don't keep fd on fork(), so that it can be closed when the parent
 	 * process get terminated. */
-	int flags = fcntl(fd, F_GETFD);
-	if (flags < 0)
-		abortmsgerrno("cannot get flags of socket");
-	if (fcntl(fd, F_SETFD, flags | FD_CLOEXEC) < 0)
-		abortmsgerrno("cannot set flags of socket");
+	fsetcloexec(fd);
 
 	struct sockaddr_un addr;
 	addr.sun_family = AF_UNIX;

contrib/chg/util.c

@@ -8,6 +8,7 b''
  */
 
 #include <errno.h>
+#include <fcntl.h>
 #include <signal.h>
 #include <stdarg.h>
 #include <stdio.h>
@@ -91,6 +92,15 b' void fchdirx(int dirfd)'
 		abortmsgerrno("failed to fchdir");
 }
 
+void fsetcloexec(int fd)
+{
+	int flags = fcntl(fd, F_GETFD);
+	if (flags < 0)
+		abortmsgerrno("cannot get flags of fd %d", fd);
+	if (fcntl(fd, F_SETFD, flags | FD_CLOEXEC) < 0)
+		abortmsgerrno("cannot set flags of fd %d", fd);
+}
+
 void *mallocx(size_t size)
 {
 	void *result = malloc(size);

contrib/chg/util.h

@@ -24,6 +24,7 b' void enabledebugmsg(void);'
 void debugmsg(const char *fmt, ...) PRINTF_FORMAT_;
 
 void fchdirx(int dirfd);
+void fsetcloexec(int fd);
 void *mallocx(size_t size);
 void *reallocx(void *ptr, size_t size);