CLEANUP: assorted typo fixes in the code and comments

This is 14th iteration of typo fixes
diff --git a/reg-tests/compression/lua_validation.vtc b/reg-tests/compression/lua_validation.vtc
index d74f2eb..af234b3 100644
--- a/reg-tests/compression/lua_validation.vtc
+++ b/reg-tests/compression/lua_validation.vtc
@@ -1,4 +1,4 @@
-# Checks that compression doesnt cause corruption..
+# Checks that compression doesn't cause corruption..
 
 varnishtest "Compression validation"
 #REQUIRE_VERSION=1.6