TrafficServer segfaults on shutdown because of uninitialized SPDY sessions

#0  0x0000000000516d18 in Ptr<ProxyMutex>::operator-> (this=0x18) at ../lib/ts/Ptr.h:330
No locals.
#1  0x000000000063d102 in SpdyRequest::clear (this=0xac7b08) at SpdyClientSession.cc:69
        __func__ = "clear"
#2  0x000000000063edfd in SpdyRequest::~SpdyRequest (this=0xac7b08, __in_chrg=<value optimized out>) at SpdyClientSession.h:58
No locals.
#3  0x000000000063eb46 in ClassAllocator<SpdyRequest>::._206::~._206() () at ../../lib/ts/Allocator.h:204
No symbol table info available.
#4  0x00000000006404ce in ClassAllocator<SpdyRequest>::~ClassAllocator (this=0xac7b00, __in_chrg=<value optimized out>) at ../../lib/ts/Allocator.h:118
No locals.
#5  0x0000003375c35b22 in exit () from /lib64/libc.so.6