patch 8.0.1016: gnome terminal echoes t_RC

Problem:    Gnome terminal echoes t_RC.
Solution:   Detect Gnome terminal by the version string.  Add v: variables for
            all the term responses.
diff --git a/src/eval.c b/src/eval.c
index b8e6064..b4250de 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -187,6 +187,10 @@
     {VV_NAME("t_none",		 VAR_NUMBER), VV_RO},
     {VV_NAME("t_job",		 VAR_NUMBER), VV_RO},
     {VV_NAME("t_channel",	 VAR_NUMBER), VV_RO},
+    {VV_NAME("termrgbresp",	 VAR_STRING), VV_RO},
+    {VV_NAME("termu7resp",	 VAR_STRING), VV_RO},
+    {VV_NAME("termstyleresp",	VAR_STRING), VV_RO},
+    {VV_NAME("termblinkresp",	VAR_STRING), VV_RO},
 };
 
 /* shorthand */