add coverity badge

README.md

@@ -6,7 +6,7 @@ See doc/crypt.pdf for a detailed documentation
 Project Status
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-develop: [![Build Status](https://api.travis-ci.org/libtom/libtomcrypt.png?branch=develop)](https://travis-ci.org/libtom/libtomcrypt) [![Coverage Status](https://coveralls.io/repos/libtom/libtomcrypt/badge.png?branch=develop)](https://coveralls.io/r/libtom/libtomcrypt)
+develop: [![Build Status](https://api.travis-ci.org/libtom/libtomcrypt.png?branch=develop)](https://travis-ci.org/libtom/libtomcrypt) [![Coverage Status](https://coveralls.io/repos/libtom/libtomcrypt/badge.png?branch=develop)](https://coveralls.io/r/libtom/libtomcrypt) [![Coverity Scan Build Status](https://scan.coverity.com/projects/487/badge.svg)](https://scan.coverity.com/projects/487)
 
 Submitting patches
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