Fix Bug 923: generated modules init/clear unused decimal constants

[ddeclerck]

That should address https://sourceforge.net/p/gnucobol/bugs/923/.

Passes all of the testsuite.

[GitMensch]

Thank you for this well done PR.

There are only minor adjustments needed. Once there is a "go" for committing to svn ("soon"), I suggest to first commit this, then the other PR of yours.

[codecov-commenter]

Codecov Report

Merging #115 (909c3cc) into gcos4gnucobol-3.x (c0d64ad) will increase coverage by 0.00%.
The diff coverage is 100.00%.

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@@                Coverage Diff                 @@
##           gcos4gnucobol-3.x     #115   +/-   ##
==================================================
  Coverage              65.74%   65.74%           
==================================================
  Files                     32       32           
  Lines                  59092    59099    +7     
  Branches               15575    15573    -2     
==================================================
+ Hits                   38849    38856    +7     
  Misses                 14262    14262           
  Partials                5981     5981           

Files	Coverage Δ
cobc/codegen.c	76.01% <100.00%> (+0.02%)	⬆️
cobc/typeck.c	65.28% <100.00%> (ø)

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