Can't compile hprof without opcodes.h opcodes_length, and jvm.h.

These were used to access the standard class constants for opcodes and
constant pool values. Too bad we can't provide these in general for
native code users. BCI will create a bigger need for these.

something like opcodes.h, opcodes.length, and jvm.h public#include files, or something like them... Not functions as much as macrosand constant values.