Don't initialize NSS before calling SSL_ClearSessionCache.

tools/valgrind/memcheck/suppressions.txt

 # There are four kinds of suppressions in this file.
 # 1. third party stuff we have no control over
 #
 # 2. intentional unit test errors, or stuff that is somehow a false positive
 # in our own code, or stuff that is so trivial it's not worth fixing
 #
 # 3. Suppressions for real chromium bugs that are not yet fixed.
 # These should all be in chromium's bug tracking system (but a few aren't yet).
 # Periodically we should sweep this file and the bug tracker clean by
 # running overnight and removing outdated bugs/suppressions.
@@ skipping 959 matching lines @@
    Memcheck:Leak
    fun:calloc
    ...
    fun:PR_NewLock
    ...
    fun:InitSessionCacheLocks
    fun:initSessionCacheLocksLazily
    fun:PR_CallOnce
    fun:ssl_InitSessionCacheLocks
    fun:lock_cache
-   fun:ssl_LookupSID
-   fun:ssl2_BeginClientHandshake
-   fun:ssl_Do1stHandshake
-   fun:SSL_ForceHandshake
-   fun:_ZN3net18SSLClientSocketNSS11DoHandshakeEv
-   fun:_ZN3net18SSLClientSocketNSS15DoHandshakeLoopEi
 }
 {
    # Intentionally leaking NSS to prevent shutdown crashes
    bug_77990 (Intentional)
    Memcheck:Leak
    fun:calloc
    ...
    fun:error_get_my_stack
    fun:nss_ClearErrorStack
    fun:NSSArena_Destroy
@@ skipping 4351 matching lines @@
    obj:/lib/libselinux.so.1
    obj:/lib/libselinux.so.1
 }
 {
    bug_todo_grep
    Memcheck:Leak
    fun:malloc
    obj:/bin/grep
    obj:/bin/grep
 }