[LyX/master] Fix compilation on Visual C++.

[Thibaut Cuvelier]

commit 92b9c82deac647bfba853d3402082e151da566ec
Author: Thibaut Cuvelier <tcuvelier at lyx.org>
Date:   Mon Oct 12 19:21:58 2020 +0200

    Fix compilation on Visual C++.
    
    Without this patch, there would be errors like these (warnings turned into errors):
    
    D:\LyX\lyx-unstable\src\frontends\qt\GuiView.cpp(2413): error C4101: 'e': unreferenced local variable
    D:\LyX\lyx-unstable\src\frontends\qt\GuiView.cpp(4879): error C4101: 'ex': unreferenced local variable
---
 src/frontends/qt/GuiView.cpp |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/frontends/qt/GuiView.cpp b/src/frontends/qt/GuiView.cpp
index 2da9ce3..919c9e1 100644
--- a/src/frontends/qt/GuiView.cpp
+++ b/src/frontends/qt/GuiView.cpp
@@ -2410,7 +2410,7 @@ Buffer * GuiView::loadDocument(FileName const & filename, bool tolastfiles)
 	Buffer * newBuffer = nullptr;
 	try {
 		newBuffer = checkAndLoadLyXFile(filename);
-	} catch (ExceptionMessage const & e) {
+	} catch (ExceptionMessage const &) {
 		setBusy(false);
 		throw;
 	}
@@ -4876,7 +4876,7 @@ void GuiView::doShowDialog(QString const & qname, QString const & qdata,
 			}
 		}
 	}
-	catch (ExceptionMessage const & ex) {
+	catch (ExceptionMessage const &) {
 		d.in_show_ = false;
 		throw;
 	}