Convert real array index to integer.
Convert real array index to integer.

This patch converts a constant real index to an integer value when
defining an array. This can happen when using 2**8 which returns a
real value since the operands are signed.

CastMi/iverilog,themperek/iverilog,CastMi/iverilog,CastMi/iverilog,themperek/iverilog,themperek/iverilog