patch 8.2.0156: various typos in source files and tests

Problem:    Various typos in source files and tests.
Solution:   Fix the typos. (Emir Sari, closes #5532)
diff --git a/src/os_win32.c b/src/os_win32.c
index 844d794..6bbd492 100644
--- a/src/os_win32.c
+++ b/src/os_win32.c
@@ -6927,7 +6927,7 @@
 	return 0;
     pStackBase = (BYTE*)mbi.AllocationBase;
 
-    // ...and the page thats min_stack_req pages away from stack base; this is
+    // ...and the page that's min_stack_req pages away from stack base; this is
     // the lowest page we could use.
     pLowestPossiblePage = pStackBase + MIN_STACK_WINNT * nPageSize;