patch 8.1.1541: check for ASAN is not reliable

Problem:    Check for ASAN is not reliable.
Solution:   Check the version output. (Dominique Pelle, closes #4543)
diff --git a/src/testdir/test_memory_usage.vim b/src/testdir/test_memory_usage.vim
index eadd4ea..519ac4b 100644
--- a/src/testdir/test_memory_usage.vim
+++ b/src/testdir/test_memory_usage.vim
@@ -6,7 +6,7 @@
 if has('gui_running')
   throw 'Skipped, does not work in GUI'
 endif
-if $ASAN_OPTIONS !=# ''
+if execute('version') =~# '-fsanitize=[a-z,]*\<address\>'
   " Skip tests on Travis CI ASAN build because it's difficult to estimate
   " memory usage.
   throw 'Skipped, does not work with ASAN'
diff --git a/src/version.c b/src/version.c
index 7e9cac3..abafa7e 100644
--- a/src/version.c
+++ b/src/version.c
@@ -778,6 +778,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1541,
+/**/
     1540,
 /**/
     1539,