/usr/include/sbml/packages/fbc/ is in libsbml5-dev 5.12.0+dfsg-3.
This file is owned by root:root, with mode 0o755.
..
/usr/include/sbml/packages/fbc/common/
/usr/include/sbml/packages/fbc/common/FbcExtensionTypes.h
/usr/include/sbml/packages/fbc/common/fbcfwd.h
/usr/include/sbml/packages/fbc/extension/
/usr/include/sbml/packages/fbc/extension/FbcExtension.h
/usr/include/sbml/packages/fbc/extension/FbcModelPlugin.h
/usr/include/sbml/packages/fbc/extension/FbcReactionPlugin.h
/usr/include/sbml/packages/fbc/extension/FbcSBMLDocumentPlugin.h
/usr/include/sbml/packages/fbc/extension/FbcSpeciesPlugin.h
/usr/include/sbml/packages/fbc/sbml/
/usr/include/sbml/packages/fbc/sbml/Association.h
/usr/include/sbml/packages/fbc/sbml/FbcAnd.h
/usr/include/sbml/packages/fbc/sbml/FbcAssociation.h
/usr/include/sbml/packages/fbc/sbml/FbcOr.h
/usr/include/sbml/packages/fbc/sbml/FluxBound.h
/usr/include/sbml/packages/fbc/sbml/FluxObjective.h
/usr/include/sbml/packages/fbc/sbml/GeneAssociation.h
/usr/include/sbml/packages/fbc/sbml/GeneProduct.h
/usr/include/sbml/packages/fbc/sbml/GeneProductAssociation.h
/usr/include/sbml/packages/fbc/sbml/GeneProductRef.h
/usr/include/sbml/packages/fbc/sbml/Objective.h
/usr/include/sbml/packages/fbc/util/
/usr/include/sbml/packages/fbc/util/CobraToFbcConverter.h
/usr/include/sbml/packages/fbc/util/FbcToCobraConverter.h
/usr/include/sbml/packages/fbc/util/FbcV1ToV2Converter.h
/usr/include/sbml/packages/fbc/util/FbcV2ToV1Converter.h
/usr/include/sbml/packages/fbc/validator/
/usr/include/sbml/packages/fbc/validator/FbcConsistencyValidator.h
/usr/include/sbml/packages/fbc/validator/FbcIdentifierConsistencyValidator.h
/usr/include/sbml/packages/fbc/validator/FbcSBMLError.h
/usr/include/sbml/packages/fbc/validator/FbcSBMLErrorTable.h
/usr/include/sbml/packages/fbc/validator/FbcValidator.h
/usr/include/sbml/packages/fbc/validator/constraints/
/usr/include/sbml/packages/fbc/validator/constraints/FluxBoundsConsistent.h
/usr/include/sbml/packages/fbc/validator/constraints/UniqueGeneProductLabels.h
/usr/include/sbml/packages/fbc/validator/constraints/UniqueModelWideIds.h