patch 8.0.0786: build failures on Travis

Problem:    Build failures on Travis.
Solution:   Go back to precise termporarily.  Disable coverage with clang.
diff --git a/src/version.c b/src/version.c
index d66326e..174524a 100644
--- a/src/version.c
+++ b/src/version.c
@@ -770,6 +770,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    786,
+/**/
     785,
 /**/
     784,