Enabling jenkins code coverage

Change-Id: If69a83ffcf0450ac06f7dab17bf862e36aef37ed
Refs: #3434
diff --git a/wscript b/wscript
index 551c572..fc24ded 100644
--- a/wscript
+++ b/wscript
@@ -9,7 +9,7 @@
 
     opt.load(['compiler_c', 'compiler_cxx', 'gnu_dirs'])
 
-    opt.load(['default-compiler-flags', 'boost',
+    opt.load(['default-compiler-flags', 'coverage', 'boost',
               'doxygen', 'sphinx_build'],
               tooldir=['.waf-tools'])
 
@@ -42,6 +42,9 @@
                    " (http://redmine.named-data.net/projects/nfd/wiki/Boost_FAQ)")
         return
 
+    # Loading "late" to prevent tests to be compiled with profiling flags
+    conf.load('coverage')
+
     conf.write_config_header('src/config.h')
 
 def build (bld):