Fix some compiler warnings:

- suggest braces around empty body in an 'if' statement
- comparison of unsigned expression >= 0 is always true
- comparison of unsigned expression < 0 is always false

Please review carefully.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@954641 13f79535-47bb-0310-9956-ffa450edef68