build+ci: add code coverage support

This commit also adds GlobalConfigurationFixture to ensure that running
unit tests doesn't interact with system configuration (e.g., doesn't use
or alter user certificates).

Change-Id: I621ce14425a777c94d41b8132cd2858d91235b4d
Refs: #3808
diff --git a/.jenkins.d/10-build.sh b/.jenkins.d/10-build.sh
index 7f885fb..f0df3eb 100755
--- a/.jenkins.d/10-build.sh
+++ b/.jenkins.d/10-build.sh
@@ -27,7 +27,7 @@
 
 # Configure/build in debug mode with tests
 if [[ $JOB_NAME == *"code-coverage" ]]; then
-    COVERAGE="" # TODO add code coverage support
+    COVERAGE="--with-coverage"
 elif ! has OSX-10.9 $NODE_LABELS && ! has OSX-10.11 $NODE_LABELS; then
     ASAN="--with-sanitizer=address"
 fi