patch 8.0.1841: HP-UX does not have setenv()

Problem:    HP-UX does not have setenv().
Solution:   Use vim_setenv(). (John Marriott)
diff --git a/src/version.c b/src/version.c
index 34b0113..67a6acf 100644
--- a/src/version.c
+++ b/src/version.c
@@ -762,6 +762,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1841,
+/**/
     1840,
 /**/
     1839,