[vte] libc: glue: Implement swap for FD

[Christian Persch <chpe src gnome org>]

commit 18912ef4fee8179c9fd2340e8e072f88bc6eda94
Author: Christian Persch <chpe src gnome org>
Date:   Wed May 27 21:17:04 2020 +0200

    libc: glue: Implement swap for FD

 src/libc-glue.hh | 7 +++++++
 1 file changed, 7 insertions(+)
---
diff --git a/src/libc-glue.hh b/src/libc-glue.hh
index 1f4c46da..3e445513 100644
--- a/src/libc-glue.hh
+++ b/src/libc-glue.hh
@@ -92,6 +92,12 @@ public:
                 }
         }
 
+        /* C++20 constexpr */ void swap(FD& other)
+        {
+                using std::swap;
+                swap(m_fd, other.m_fd);
+        }
+
 private:
         int m_fd{-1};
 
@@ -101,6 +107,7 @@ constexpr bool operator==(FD const& lhs, FD const& rhs) noexcept { return lhs.ge
 constexpr bool operator==(FD const& lhs, int rhs) noexcept { return lhs.get() == rhs; }
 constexpr bool operator!=(FD const& lhs, FD const& rhs) noexcept { return !(lhs == rhs); }
 constexpr bool operator!=(FD const& lhs, int rhs) noexcept { return !(lhs == rhs); }
+/* C++20 constexpr */ inline void swap(FD& lhs, FD& rhs) noexcept { lhs.swap(rhs); }
 
 /* FD convenience functions */