Optimize package lookups where the first part is lexical; also fixes them inside of BEGIN blocks.
Optimize package lookups where the first part is lexical; also fixes them inside of BEGIN blocks.

cygx/nqp,cygx/nqp,cygx/nqp,cygx/nqp,cygx/nqp,cygx/nqp,cygx/nqp,cygx/nqp