[LyX/master] If using GNU Global, ignore the created database

[Kornel Benko]

commit 6259060dd32e15a8333ffe95db62f397cbaebb12
Author: Kornel Benko <kornel at lyx.org>
Date:   Sat Dec 14 13:42:06 2019 +0100

    If using GNU Global, ignore the created database
---
 .gitignore |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/.gitignore b/.gitignore
index fb63569..3aca5f7 100644
--- a/.gitignore
+++ b/.gitignore
@@ -20,3 +20,6 @@ build/
 CMakeLists.txt.user
 .dirstamp
 /src/tex2lyx/test/*.lyx.tex
+GPATH
+GRTAGS
+GTAGS