cmake HAVE_UNISTD_H_ examples

GenericMappingTools/gmt cmake/modules/ConfigureChecks.cmake :121 

check_include_file (unistd.h            HAVE_UNISTD_H_)

GenericMappingTools/gmt cmake/modules/ConfigureChecks.cmake :195 

else (HAVE_UNISTD_H_)

GenericMappingTools/gmt cmake/modules/ConfigureChecks.cmake :199 

endif (HAVE_UNISTD_H_)

GenericMappingTools/gmt cmake/modules/ConfigureChecks.cmake :246 

endif (HAVE_UNISTD_H_)