Spelling fixes in comments, documentation, tests and examples

By klemens <ka7@github.com>

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/docs/style-guide.txt b/docs/style-guide.txt
index 10ed893..9eed7f1 100644
--- a/docs/style-guide.txt
+++ b/docs/style-guide.txt
@@ -329,7 +329,7 @@
 a real storage in rodata for it! (Hopefully, newer gcc will get better
 at it...).  With "define", you have slight risk of polluting namespace
 (#define doesn't allow you to redefine the name in the inner scopes),
-and complex "define" are evaluated each time they uesd, not once
+and complex "define" are evaluated each time they used, not once
 at declarations like enums. Also, the preprocessor does _no_ type checking
 whatsoever, making it much more error prone.