Add a Diagnostic when affecting PIC X/Group to numeric with USAGE

[delevoye]

When moving a PIC X/Group to an numeric with an USAGE (COMP/BINARY...), the result is unpredictable and might lead to an ABEND at runtime when using the numeric variable.
To prevent such a situation, a warning should be issued.

Example:

       IDENTIFICATION DIVISION.
       PROGRAM-ID. Pgm.
       DATA DIVISION.
       WORKING-STORAGE SECTION.
       01 alpha        pic X(03).
       01 alpha2       pic X(03).

       01 num1         pic 9(03).
       01 num2         comp-1.
       01 num3         comp-2.
       01 num4         pic 9(03) comp-3.
       01 num5         pic 9(03) comp-4.
       01 num6         pic 9(03) comp-5.
       01 num7         pic 9(03) packed-decimal.
       01 num8         pic 9(03) binary.
       01 num9         pic 9(03) comp.

       PROCEDURE DIVISION.

      *   Ok
           move alpha          to alpha2

      *   Ok because num1 is an extended numeric
           move alpha          to num1
      *   Ko because it is a comp variable
           move alpha          to num2
      *   Ko because it is a comp variable
           move alpha          to num3
      *   Ko because it is a comp variable
           move alpha          to num4
      *   Ko because it is a comp variable
           move alpha          to num5
      *   Ko because it is a comp variable
           move alpha          to num6
      *   Ko because it is a comp variable
           move alpha          to num7
      *   Ko because it is a comp variable
           move alpha          to num8
      *   Ko because it is a comp variable
           move alpha          to num9

      *   Ok because it is a function
           move FUNCTION WHEN-COMPILED          to num4
      *   Ok because it is a function
           move FUNCTION CURRENT-DATE           to num4
      *   Ok because it is a function
           move LENGTH                   alpha  to num4
      *   Ok because it is a function
           move LENGTH OF                alpha  to num4

           GOBACK
           .

       END PROGRAM Pgm.