Stop generating internal __cpctor function so it's just redundant

Instead we can directly memcpy the object, then call the postblit.
fix 13776 - Incorrect "recursive alias declaration" error with `__traits(compiles, ...)`
fix Issue 12780 - Multiplying integer array by scalar double fails

Support upcasting slice elements in array operations.

1. The tweak in the buildArrayIdent() retains backward compatibility.
a) If no element upcasting exists in array operation, the generated function name is not changed.
  double_res[] = double_val * double_arr[];
  // _arrayExpSliceMulSliceAssign_d
b) If upcasting slice elements is necessary, it will be encoded by the postfix "Of" + element-type-deco
  double_res[] = double_val * int_arr[];
  // _arrayExpSlice'Ofi'MulSliceAssign_d

2. Even if the whole array operation requires double element, the sub array operations can be processed by int.
  double_res[] = (int_val ^ int_arr[]) * double_val;
  // typeof(int_val ^ int_arr[]) == int[]
Merge pull request #4172 from 9rnsr/fix13776

[REG2.067a] 13776 - Incorrect "recursive alias declaration" error with `__traits(compiles, ...)`
Merge pull request #4183 from 9rnsr/remove_cpctor

Stop generating internal __cpctor function
Merge pull request #4218 from 9rnsr/fix12780

Issue 12780 - Multiplying integer array by scalar double fails