[lsan] Unbreak standalone LSan's initialization by making it more like ASan's.

No longer allow interceptors to be called during initialization, use the preinit
array (instead of initializing at the first call to an intercepted function) and
adopt the calloc() hack from ASan.

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@195642 91177308-0d34-0410-b5e6-96231b3b80d8