[gtksourceview] recognise *.glsl files

[Christian Hergert <chergert src gnome org>]

commit 9bdef128bb418f2b42bf47c36bbae305e012f40d
Author: Elias Aebi <eyelash users noreply github com>
Date:   Tue Sep 4 11:56:16 2018 +0200

    recognise *.glsl files

 data/language-specs/glsl.lang | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/data/language-specs/glsl.lang b/data/language-specs/glsl.lang
index a7be53fe..6825ab2e 100644
--- a/data/language-specs/glsl.lang
+++ b/data/language-specs/glsl.lang
@@ -30,7 +30,7 @@ http://www.opengl.org/registry/doc/GLSLangSpec.4.00.7.pdf
 <language id="glsl" _name="OpenGL Shading Language" version="2.0" _section="Source">
 
   <metadata>
-    <property name="globs">*.glslv;*.glslf</property>
+    <property name="globs">*.glslv;*.glslf;*.glsl</property>
     <property name="line-comment-start">//</property>
     <property name="block-comment-start">/*</property>
     <property name="block-comment-end">*/</property>