various files - fix some alerts raised by lgtm code analysis

This patch fixes several issues reported by the lgtm code analysis tool:

https://lgtm.com/projects/g/asterisk/asterisk

Not all reported issues were addressed in this patch. This patch mostly fixes
confirmed reported errors, potential problematic code points, and a few other
"low hanging" warnings or recommendations found in core supported modules.
These include, but are not limited to the following:

* innapropriate stack allocation in loops
* buffer overflows
* variable declaration "hiding" another variable declaration
* comparisons results that are always the same
* ambiguously signed bit-field members
* missing header guards

Change-Id: Id4a881686605d26c94ab5409bc70fcc21efacc25

apps/app_cdr.c

@@ -119,13 +119,13 @@ struct app_cdr_message_payload {
 	/*! The name of the channel to be manipulated */
 	const char *channel_name;
 	/*! Disable the CDR for this channel */
-	int disable:1;
+	unsigned int disable:1;
 	/*! Re-enable the CDR for this channel */
-	int reenable:1;
+	unsigned int reenable:1;
 	/*! Reset the CDR */
-	int reset:1;
+	unsigned int reset:1;
 	/*! If reseting the CDR, keep the variables */
-	int keep_variables:1;
+	unsigned int keep_variables:1;
 };
 
 static void appcdr_callback(void *data, struct stasis_subscription *sub, struct stasis_message *message)