Fix includes for BDD_GUARDS

[tautschnig]

guard_bddt needs bdd_exprt, but failed to include the necessary header.

Fixes: #7726

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[codecov]

Codecov Report

Patch and project coverage have no change.

Comparison is base (cfcfcf6) 78.57% compared to head (1315b61) 78.57%.

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #7727   +/-   ##
========================================
  Coverage    78.57%   78.57%           
========================================
  Files         1685     1685           
  Lines       192962   192979   +17     
========================================
+ Hits        151624   151639   +15     
- Misses       41338    41340    +2     

Impacted Files	Coverage Δ
.../goto-instrument/goto_instrument_parse_options.cpp	72.14% <ø> (ø)

... and 1 file with indirect coverage changes

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