[libglnx] Add glnx_steal_fd

[Alexander Larsson <alexl src gnome org>]

commit 4e9969998b3d385fc007fa5deba5f256aa7b2e95
Author: Alexander Larsson <alexl redhat com>
Date:   Fri Dec 11 15:56:06 2015 +0100

    Add glnx_steal_fd
    
    This is very useful in combination with glnx_close_fd
    
    https://bugzilla.gnome.org/show_bug.cgi?id=757611

 glnx-local-alloc.h |    8 ++++++++
 1 files changed, 8 insertions(+), 0 deletions(-)
---
diff --git a/glnx-local-alloc.h b/glnx-local-alloc.h
index a193e60..af5af4b 100644
--- a/glnx-local-alloc.h
+++ b/glnx-local-alloc.h
@@ -211,4 +211,12 @@ glnx_cleanup_close_fdp (int *fdp)
  */
 #define glnx_fd_close __attribute__((cleanup(glnx_cleanup_close_fdp)))
 
+static inline int
+glnx_steal_fd (int *fdp)
+{
+  int fd = *fdp;
+  *fdp = -1;
+  return fd;
+}
+
 G_END_DECLS