patch 8.0.1690: not easy to run one test with gvim instead of vim

Problem:    Not easy to run one test with gvim instead of vim.
Solution:   Add VIMTESTTARGET in Makefile.
diff --git a/src/version.c b/src/version.c
index 196d61c..265e6e9 100644
--- a/src/version.c
+++ b/src/version.c
@@ -763,6 +763,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1690,
+/**/
     1689,
 /**/
     1688,