patch 8.2.3637: typos in test files

Problem:    Typos in test files.
Solution:   Correct the typos. (Dominique Pellé, closes #9175)
diff --git a/src/testdir/test_normal.vim b/src/testdir/test_normal.vim
index 3e3f663..fd2e2ec 100644
--- a/src/testdir/test_normal.vim
+++ b/src/testdir/test_normal.vim
@@ -1243,7 +1243,7 @@
   norm! j
   call assert_equal('52', getline('.'))
 
-  " zA on a opened fold when foldenable is not set
+  " zA on an opened fold when foldenable is not set
   50
   set nofoldenable
   norm! zA
@@ -1601,7 +1601,7 @@
 
   let not_gnu_man = has('mac') || has('bsd')
   if not_gnu_man
-    " In MacOS and BSD, the option for specifying a pager is different
+    " In macOS and BSD, the option for specifying a pager is different
     set keywordprg=man\ -P\ cat
   else
     set keywordprg=man\ --pager=cat
@@ -2394,7 +2394,7 @@
   call assert_equal('foo       first line', getline(1))
   set virtualedit&
 
-  " Test for aboring a g command using CTRL-\ CTRL-G
+  " Test for aborting a g command using CTRL-\ CTRL-G
   exe "normal! g\<C-\>\<C-G>"
   call assert_equal('foo       first line', getline('.'))