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/gui_mac.c b/src/gui_mac.c
index 3dfb939..875b3ec 100644
--- a/src/gui_mac.c
+++ b/src/gui_mac.c
@@ -2919,7 +2919,7 @@
 
     (void)FSGetCatalogInfo(&applFSRef, kFSCatInfoNone, NULL, NULL, &applDir, NULL);
 
-    // This technic return NIL when we disallow_gui
+    // This technique returns NIL when we disallow_gui
 # endif
     exe_name = FullPathFromFSSpec_save(applDir);
 #endif