libxl: use libxl_fd_set_{cloexec,nonblock} helpers

... instead of open-coding them or not using them at all. This in
particular fixes a build (and presumably also runtime) problem on old
enough libc due to the recent introduction of a use of O_CLOEXEC. The
other two changes are only of cleanup kind.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
---
v2: Drop unnecessary logging (and result value corruption in the
    libxl__xc_domain_restore_done() case).

--- 2014-07-25.orig/tools/libxl/libxl_create.c	2014-07-25 10:41:10.000000000 +0200
+++ 2014-07-25/tools/libxl/libxl_create.c	2014-07-28 09:23:18.000000000 +0200
@@ -977,7 +977,7 @@ void libxl__xc_domain_restore_done(libxl
     libxl_ctx *ctx = libxl__gc_owner(gc);
     char **vments = NULL, **localents = NULL;
     struct timeval start_time;
-    int i, esave, flags;
+    int i, esave;
 
     /* convenience aliases */
     const uint32_t domid = dcs->guest_domid;
@@ -1045,17 +1045,7 @@ out:
     }
 
     esave = errno;
-
-    flags = fcntl(fd, F_GETFL);
-    if (flags == -1) {
-        LIBXL__LOG_ERRNO(ctx, LIBXL__LOG_ERROR, "unable to get flags on restore fd");
-    } else {
-        flags &= ~O_NONBLOCK;
-        if (fcntl(fd, F_SETFL, flags) == -1)
-            LIBXL__LOG_ERRNO(ctx, LIBXL__LOG_ERROR, "unable to put restore fd"
-                         " back to blocking mode");
-    }
-
+    libxl_fd_set_nonblock(ctx, fd, 0);
     errno = esave;
     domcreate_rebuild_done(egc, dcs, ret);
 }
--- 2014-07-25.orig/tools/libxl/libxl_qmp.c	2014-07-25 10:41:10.000000000 +0200
+++ 2014-07-25/tools/libxl/libxl_qmp.c	2014-07-25 16:17:40.000000000 +0200
@@ -358,19 +358,14 @@ static int qmp_open(libxl__qmp_handler *
                     int timeout)
 {
     int ret;
-    int flags = 0;
     int i = 0;
 
     qmp->qmp_fd = socket(AF_UNIX, SOCK_STREAM, 0);
     if (qmp->qmp_fd < 0) {
         return -1;
     }
-    if ((flags = fcntl(qmp->qmp_fd, F_GETFL)) == -1) {
-        flags = 0;
-    }
-    if (fcntl(qmp->qmp_fd, F_SETFL, flags | O_NONBLOCK) == -1) {
-        return -1;
-    }
+    ret = libxl_fd_set_nonblock(qmp->ctx, qmp->qmp_fd, 1);
+    if (ret) return -1;
     ret = libxl_fd_set_cloexec(qmp->ctx, qmp->qmp_fd, 1);
     if (ret) return -1;
 
--- 2014-07-25.orig/tools/libxl/libxl_utils.c	2014-07-25 10:41:10.000000000 +0200
+++ 2014-07-25/tools/libxl/libxl_utils.c	2014-07-28 09:24:38.000000000 +0200
@@ -1047,11 +1047,16 @@ int libxl__random_bytes(libxl__gc *gc, u
     int fd;
     int ret;
 
-    fd = open(dev, O_RDONLY | O_CLOEXEC);
+    fd = open(dev, O_RDONLY);
     if (fd < 0) {
         LOGE(ERROR, "failed to open \"%s\"", dev);
         return ERROR_FAIL;
     }
+    ret = libxl_fd_set_cloexec(CTX, fd, 1);
+    if (ret) {
+        close(fd);
+        return ERROR_FAIL;
+    }
 
     ret = libxl_read_exactly(CTX, fd, buf, len, dev, NULL);