Bug 925729 - don't use JS_BITS_PER_WORD_LOG2 in BytecodeEmitter.cpp; r=njn

We have JS_BITMAP_NBITS now, and we can rely on the compiler to fold multiplication
and division into shifts.

The casts are for avoiding signed-to-unsigned comparison warnings, and for making
sure the memset length is properly converted into a shift.
Bug 924891 - don't use JS_BITS_PER_WORD in jscrashreport.cpp; r=njn
Bug 925733 - don't use JS_BITS_PER_WORD_LOG2 for jit caches; r=jandem
Bug 925807 - define JS_BITS_PER_WORD in terms of JS_64BIT; r=njn
Bug 925879 - use JS_BITS_PER_WORD instead of JS_BYTES_PER_WORD in HashTable.h; r=njn
Bug 925879 - use sizeof(void*) instead of JS_BYTES_PER_WORD in jsfriendapi.h; r=njn
Bug 925879 - remove vestigal JS_BYTES_PER_WORD/JS_BITS_PER_WORD_LOG2 definitions from jscpucfg.h; r=njn
Bug 781171 - delete JS_BYTES_PER_WORD/JS_BITS_PER_WORD from configure.in; r=glandium
Bug 927406 - check whether we've updated _slowSQLStartup before using its fields; r=vladan