Add more suppression rules for NSS leaks.

This change suppresses NSS leaks happening after changing the "Chromium OS Heapcheck" bot from i386 to x86_64.

TBR=thakis
BUG=51988
TEST=make the "Chromium OS Heapcheck" bot greener.
Review URL: https://chromiumcodereview.appspot.com/10206012

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@133645 0039d316-1c4b-4281-b951-d872f2087c98

tools/heapcheck/suppressions.txt

@@ -124,6 +124,28 @@
    ...
    fun:net::CertDatabaseNSSTest::SetUp
 }
+{
+   bug_51988_h
+   Heapcheck:Leak
+   fun:sqlite3MemMalloc
+   ...
+   fun:chromeos::OncNetworkParser::ParseServerOrCaCertificate
+   fun:chromeos::OncNetworkParser::ParseCertificate
+}
+{
+   bug_51988_i
+   Heapcheck:Leak
+   fun:sqlite3MemMalloc
+   fun:net::X509Certificate::GetDefaultNickname
+}
+{
+   bug_51988_j
+   Heapcheck:Leak
+   fun:sqlite3MemMalloc
+   fun:chromeos::*::ListCertsInSlot
+   ...
+   fun:chromeos::*::TearDown
+}
 {
    bug_66941_a
    Heapcheck:Leak