Avoid use of reserved C99 keyword "bool" as a variable name

[jengelh]

gcc15 comes with -std=c23 by default. The C99 bool keyword is still in effect. C23 has only deprecated it, not removed it.

gcc-15 output:

src/fplsa4.c: In function ‘ReadBooleanFromFile’:
src/fplsa4.c:7013:7: error: ‘bool’ cannot be used here
 7013 |   int bool;
src/fplsa4.c:7013:7: note: ‘bool’ is a keyword with ‘-std=c23’ onwards
src/fplsa4.c:7013:3: warning: useless type name in empty declaration
 7013 |   int bool;

gcc-14 output:

src/fplsa4.c: In function ‘ReadBooleanFromFile’:
src/fplsa4.c:7027:10: warning: ‘bool’ may be used uninitialized [-Wmaybe-uninitialized]
 7027 |   return bool;

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 26.63%. Comparing base (0fa0a22) to head (9f93c5b).
⚠️ Report is 2 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master      #13      +/-   ##
==========================================
+ Coverage   26.61%   26.63%   +0.02%     
==========================================
  Files           2        2              
  Lines        3660     3661       +1     
  Branches      730      730              
==========================================
+ Hits          974      975       +1     
  Misses       2561     2561              
  Partials      125      125              

Files with missing lines	Coverage Δ
src/fplsa4.c	23.19% <100.00%> (+0.02%)	⬆️

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[fingolfin]

Duplicate of #12