[LyX/master] Revert "Remove unneeded std::move"

[Jean-Marc Lasgouttes]

commit 41c0fc171a81bb371515296d735bb85b03962d0f
Author: Jean-Marc Lasgouttes <lasgout...@lyx.org>
Date:   Fri Jun 7 19:41:16 2019 +0200

    Revert "Remove unneeded std::move"
    
    This confuses gcc 4.9
    
    This reverts commit 44e88a4c1324fed447ab5510734c741d18f856c0.
---
 src/MetricsInfo.cpp |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/src/MetricsInfo.cpp b/src/MetricsInfo.cpp
index b33c368..0e90876 100644
--- a/src/MetricsInfo.cpp
+++ b/src/MetricsInfo.cpp
@@ -74,7 +74,7 @@ Changer MetricsBase::changeFontSet(string const & name)
            && ((isTextFont(oldname) && oldcolor != Color_foreground)
                || (isMathFont(oldname) && oldcolor != Color_math)))
                font.setColor(oldcolor);
-       return rc;
+       return move(rc);
 }