A new implementation of sqlite3VdbeMakeLabel() is faster and makes fewer

A new implementation of sqlite3VdbeMakeLabel() is faster and makes fewer
memory allocations by deferring memory allocation until
sqlite3VdbeResolveLabel() is called, at which point the code generator has
a better idea of how big the relocation table needs to be.
The sqlite3VdbeMakeLabel() routine now takes a Parse* parameter instead of
Vdbe*.

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