Library does not link to gctpc

[AlysonStahl-NOAA]

Using the static or shared libraries results in several undefined references to functions in the gctpc subfolder. That's because the link to gctpc is commented out for the libraries:

target_link_libraries(wgrib2_exe PRIVATE gctpc -lm)

if(BUILD_LIB)
  set(headers wgrib2_api.h wgrib2.h ${CMAKE_BINARY_DIR}/wgrib2/wgrib2_meta.h)
##   target_link_libraries(wgrib2_lib PUBLIC gctpc)
  set_target_properties(wgrib2_lib PROPERTIES PUBLIC_HEADER "${headers}")
  target_compile_definitions(wgrib2_lib PUBLIC ${definitions_list})
  
  install(
    TARGETS wgrib2_lib
    EXPORT wgrib2_exports
    LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR}
    ARCHIVE DESTINATION ${CMAKE_INSTALL_LIBDIR}
    PUBLIC_HEADER DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}
    )
  
endif()