linux-capture: Remove obsolete translation

"LockX" was added by 15fb027647 and removed by later commit 1604400e4.

plugins/linux-capture/data/locale/en-US.ini

@@ -10,6 +10,5 @@ CropLeft="Crop Left"
 CropRight="Crop Right"
 CropBottom="Crop Bottom"
 SwapRedBlue="Swap red and blue"
-LockX="Lock X server when capturing"
 IncludeXBorder="Include X Border"
 ExcludeAlpha="Use alpha-less texture format (Mesa workaround)"