Add branch coverage to coveralls statistics

Fixes #4444

[extended tests]
Reviewed-by: NRich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/4447)

.travis.yml

@@ -215,7 +215,7 @@ script:
 
 after_success:
     - if [ -n "$COVERALLS" ]; then
-          coveralls -b . --gcov gcov-5 --gcov-options '\-lp';
+          coveralls -b . --gcov gcov-5 --gcov-options '\-lpbc';
       fi;
 
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