CLEANUP: assorted typo fixes in the code and comments

These are mostly comments in the code. A few error messages were fixed
and are of low enough importance not to deserve a backport. Some regtests
were also fixed.
diff --git a/include/proto/pattern.h b/include/proto/pattern.h
index 73d3cdc..39514b1 100644
--- a/include/proto/pattern.h
+++ b/include/proto/pattern.h
@@ -51,7 +51,7 @@
 }
 
 /* This function executes a pattern match on a sample. It applies pattern <expr>
- * to sample <smp>. The function returns NULL if the sample dont match. It returns
+ * to sample <smp>. The function returns NULL if the sample don't match. It returns
  * non-null if the sample match. If <fill> is true and the sample match, the
  * function returns the matched pattern. In many cases, this pattern can be a
  * static buffer.