Support list initializers for 1D integer arrays.

[jopperm]

This is not a generic solution I yet; I mainly need this (and tested it for) writing constant registers like:

architectural_state {
  const register unsigned<8> ROT_0[4] = {31, 17, 0, 24};
  const register unsigned<8> ROT_1[4] = {24, 17, 31, 16};
  const register unsigned<32> RCON[8] =
      {0xB7E15162, 0xBF715880, 0x38B4DA56, 0x324E7738,
      0xBB1185EB, 0x4F7C7B57, 0xCFBFA1C8, 0xC2B3293D};
}

[jopperm]

@AtomCrafty Can you have a quick look, please?

[AtomCrafty]

Looks good to me for the most part. This is the correct place to perform these checks.
I believe we also need to check that all of the initializer values are constant expressions in case this is an ISA level initialization.