Reviewed by Maciej Stachowiak.

        Fixed <rdar://problem/4485644> REGRESSION: JavaScriptCore has init routines
        
        The TCMalloc module now initializes, if needed, inside GetCache() and 
        fastMallocSetIsMultiThreaded(). We leverage the same synchronization 
        technique used for enabling / disabling the single-threaded optimization 
        to synchronize initialization of the library without requiring a lock 
        for every malloc.
        
        1,251 runs of tcmalloc_unittest, 2 runs of a custom, massively multi-threaded 
        tcmalloc_unittest, and my custom version of the PLT show no regressions.
        Super-accurate JS iBench reports a .24% regression, which is right at the
        limit of its error range, so I'm declaring victory.

        * wtf/FastMalloc.cpp:
        (WTF::fastMallocSetIsMultiThreaded): Initialize, if needed. (InitModule()
        checks the "if needed" part.)
        (WTF::TCMalloc_ThreadCache::GetCache): Restored original TCMalloc code
        inside #ifdef, for posterity. Added new initialization logic.
        (WTF::TCMalloc_ThreadCache::InitModule): Call InitTSD(), since we don't
        have a static initializer to call it for us, now. This means that fastMalloc
        is not usable as a general libc allocator, but it never was, and if it were
        the general libc allocator, we wouldn't be here in the first place, so whatever.
        (WTF::TCMalloc_ThreadCache::InitTSD): Don't try to take the pageheap_lock, 
        since InitModule already has it.

WebKitTools:

        Reviewed by Maciej Stachowiak.

        Fixed <rdar://problem/4485644> REGRESSION: JavaScriptCore has init routines
        
        No more mollycoddling for you, FastMalloc.o!
        
        * Scripts/check-for-global-initializers:



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@19245 268f45cc-cd09-0410-ab3c-d52691b4dbfc