Add mtx (mutex) to test infrastructure, in order to avoid bootstrapping
complications that would result from directly using malloc_mutex.
Rename test infrastructure's thread abstraction from je_thread to thd.
Fix some header ordering issues.
Update hash from MurmurHash2 to MurmurHash3, primarily because the
latter generates 128 bits in a single call for no extra cost, which
simplifies integration with cuckoo hashing.
Implement malloc_vsnprintf() (a subset of vsnprintf(3)) as well as
several other printing functions based on it, so that formatted printing
can be relied upon without concern for inducing a dependency on floating
point runtime support. Replace malloc_write() calls with
malloc_*printf() where doing so simplifies the code.
Add name mangling for library-private symbols in the data and BSS
sections. Adjust CONF_HANDLE_*() macros in malloc_conf_init() to expose
all opt_* variable use to cpp so that proper mangling occurs.
