BUILD Try the new Coverity Scan Travis upload URL

The old one was apparently switched off recently. Let's try the new
one, which we previously moved back from because it suddenly stopped
working.

.travis_coverity.sh

@@ -14,7 +14,7 @@ PLATFORM=`uname`
 TOOL_ARCHIVE=/tmp/cov-analysis-${PLATFORM}.tgz
 TOOL_URL=https://scan.coverity.com/download/${PLATFORM}
 TOOL_BASE=/tmp/coverity-scan-analysis
-UPLOAD_URL="http://scan5.coverity.com/cgi-bin/travis_upload.py"
+UPLOAD_URL="https://scan.coverity.com/builds"
 SCAN_URL="https://scan.coverity.com"
 
 # Verify Coverity Scan run condition