patch 8.0.1791: using uint8_t does not work everywhere

Problem:    Using uint8_t does not work everywhere.
Solution:   Use char_u instead.
diff --git a/src/version.c b/src/version.c
index 467b14e..9dd2895 100644
--- a/src/version.c
+++ b/src/version.c
@@ -762,6 +762,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1791,
+/**/
     1790,
 /**/
     1789,