add note about running the test suite with valgrind

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@60029 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/www/hacking.html b/www/hacking.html
index da414d6..020d3cb 100644
--- a/www/hacking.html
+++ b/www/hacking.html
@@ -68,6 +68,9 @@
   results, and <tt>make VERBOSE=1</tt> can be used to show more detail

   about what is being run.</p>

 

+  <p>The regression suite can also be run with Valgrind by running

+  <tt>make test VG=1</tt> in the top-level clang directory.</p>

+

   <p>For more intensive changes, running

   the <a href="http://llvm.org/docs/TestingGuide.html#testsuiterun">LLVM

   Test Suite</a> with clang is recommended. Currently the best way to