Add script to run Coverity.

This will allow anyone with the Coverity scanner installed and our
authtoken to upload their own feature branch if they want to.

Main point is to get this out of the Jenkins job definition and into
something that is more developer accessible.

Doing my best to keep it /bin/sh compatible.

.gitignore

@@ -109,3 +109,7 @@ cscope.*out
 /bin/varnishtest/tests/*.log
 /bin/varnishtest/tests/*.log-t
 /bin/varnishtest/test-suite.log
+#
+# Coverity output
+/cov-int
+/myproject.tgz

devscripts/coverity-run

+#!/bin/sh
+#
+# Build Varnish under Coverity, and upload the output to Coverity Scan.
+#
+# Requires the Coverity scanner in $PATH and the upload token set in $COVTOKEN.
+#
+# See https://github.com/varnishcache/varnish-cache/wiki/Coverity-scans for overview.
+#
+
+
+if [ -z "$COVTOKEN" ]; then
+	echo "ERROR: No COVTOKEN in environment"
+	exit 1
+fi
+
+if [ -z "`which cov-build`" ]; then
+	echo "ERROR: No Coverity (cov-build) in \$PATH. Download: https://scan.coverity.com/download?tab=cxx"
+	exit 1
+fi
+
+if [ -z "$EMAIL" ]; then
+	EMAIL="varnish-dev@varnish-cache.org"
+fi
+
+
+GITREF=`git rev-parse --short HEAD`
+GITBRANCH=`git rev-parse --abbrev-ref HEAD`
+
+# Do a dirty check.
+DIRT=`git status --porcelain 2>/dev/null | egrep '^(\ M|M)' | grep -v coverity-run`
+if [ -n "$DIRT" ]; then
+	printf "ERROR: Refusing to analyse a dirty tree.\n$DIRT\n"
+	exit 2
+fi
+
+test "`basename $PWD`" = "devscripts" && cd ..
+
+make distclean || true
+test -f configure || ./autogen.sh
+./configure
+
+cov-build --dir cov-int make
+
+# the web ui seems to require the file to be called myproject.tgz. Very cute.
+tar cvfz myproject.tgz cov-int
+
+curl --form token=$COVTOKEN \
+  --form "email=$EMAIL" \
+  --form "file=@myproject.tgz" \
+  --form version="$GITREF" \
+  --form description="description=${GITBRANCH}_branch" \
+  'https://scan.coverity.com/builds?project=varnish'
+
+rm myproject.tgz