[gtksourceview] cmake.lang: recognize unset() as a variable assignment

[Sébastien Wilmet <swilmet src gnome org>]

commit 648a76a599a65126e6a329917edbc98e5b62dcf1
Author: Роман Донченко <dpb corrigendum ru>
Date:   Sun Nov 12 22:07:48 2017 +0300

    cmake.lang: recognize unset() as a variable assignment
    
    https://bugzilla.gnome.org/show_bug.cgi?id=790345

 data/language-specs/cmake.lang |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/data/language-specs/cmake.lang b/data/language-specs/cmake.lang
index 6c14234..c79541a 100644
--- a/data/language-specs/cmake.lang
+++ b/data/language-specs/cmake.lang
@@ -789,7 +789,7 @@
     </context>
 
     <context id="variable-assignment">
-      <start>\b((?i)SET)\b\s*\(\s*([\w_][\w\d_]*)</start>
+      <start>\b((?i)SET|UNSET)\b\s*\(\s*([\w_][\w\d_]*)</start>
       <end>\)</end>
       <include>
         <context sub-pattern="1" where="start" style-ref="builtin-command"/>