WIP: Make TriBITS package with raw CMake work (TriBITSPub#582)

Allow TriBITS package TribitsExampleProject/Package1 to use 100% raw CMake and
update TriBITS to allow that.

This raw CMake build mode for Package1 uses no TriBITS macros, functions, or
other functionality at all.

The only changes to TriBITS-proper needed to allow this were:

* Skip check for not calling tribits_package_postprocess() if the
  `<Package>::all_libs` target is already defined.

* Build up the list of package libraries target for the `<Project>_libs`
  target from `<Package>::all_libs` instead of `<Package>_libs` (since the
  latter does not exist for a raw CMake package).

This seems to pass all of the TriBITS tests.

NOTE: This commit does **not** yet contain the changes to TriBITS to allow
calling project() in the package's CMakeLists.txt files and still use TriBITS
macros in the package's CMakeLists.txt files.  Those changes will come later
as we add an example that calls some TriBITS functions.

tribits/core/package_arch/TribitsGlobalMacros.cmake

@@ -2072,17 +2072,20 @@ macro(tribits_configure_enabled_packages)
         tribits_trace_file_processing(PACKAGE  ADD_SUBDIR
           "${TRIBITS_PACKAGE_CMAKELIST_FILE}")
         if (NOT ${TRIBITS_PACKAGE}_SOURCE_DIR STREQUAL ${PROJECT_NAME}_SOURCE_DIR)
-          add_subdirectory(${${TRIBITS_PACKAGE}_SOURCE_DIR} ${${TRIBITS_PACKAGE}_BINARY_DIR})
+          add_subdirectory(${${TRIBITS_PACKAGE}_SOURCE_DIR}
+            ${${TRIBITS_PACKAGE}_BINARY_DIR})
         else()
           include("${TRIBITS_PACKAGE_CMAKELIST_FILE}")
         endif()
-        if (NOT ${PACKAGE_NAME}_TRIBITS_PACKAGE_POSTPROCESS)
+        if ((NOT ${PACKAGE_NAME}_TRIBITS_PACKAGE_POSTPROCESS) AND
+	    (NOT TARGET ${PACKAGE_NAME}::all_libs)
+          )
           tribits_report_invalid_tribits_usage(
             "ERROR: Forgot to call tribits_package_postprocess() in"
             " ${TRIBITS_PACKAGE_CMAKELIST_FILE}")
         endif()
 
-        list(APPEND ENABLED_PACKAGE_LIBS_TARGETS ${TRIBITS_PACKAGE}_libs)
+        list(APPEND ENABLED_PACKAGE_LIBS_TARGETS ${TRIBITS_PACKAGE}::all_libs)
         list(APPEND ${PROJECT_NAME}_LIBRARIES ${${TRIBITS_PACKAGE}_LIBRARIES})
 
         tribits_package_config_code_stop_timer(PROCESS_THIS_PACKAGE_TIME_START_SECONDS

tribits/examples/TribitsExampleProject2/packages/package1/CMakeLists.txt

@@ -32,17 +32,29 @@ else()
     add_subdirectory(test)
   endif()
 
-  # Generate the all_libs target
+  # Generate the all_libs target(s)
   add_library(Package1_all_libs INTERFACE)
   set_target_properties(Package1_all_libs PROPERTIES
     EXPORT_NAME all_libs)
   target_link_libraries(Package1_all_libs INTERFACE Package1_package1)
-  install(
-    TARGETS Package1_all_libs
+  install(TARGETS Package1_all_libs
     EXPORT ${PROJECT_NAME}
+    COMPONENT ${PROJECT_NAME}
     INCLUDES DESTINATION ${CMAKE_INSTALL_INCLUDEDIR} )
+  add_library(Package1::all_libs ALIAS Package1_all_libs)
+
+  # Generate Package1Config.cmake file for the build tree
+  set(packageBuildDirCMakePackagesDir
+    "${${CMAKE_PROJECT_NAME}_BINARY_DIR}/cmake_packages/${PROJECT_NAME}")
+  export(EXPORT ${PROJECT_NAME}
+    NAMESPACE ${PROJECT_NAME}::
+    FILE "${packageBuildDirCMakePackagesDir}/${PROJECT_NAME}ConfigTargets.cmake" )
+  configure_file(
+    "${CMAKE_CURRENT_SOURCE_DIR}/cmake/raw/Package1Config.cmake.in"
+    "${packageBuildDirCMakePackagesDir}/${PROJECT_NAME}/Package1Config.cmake"
+    @ONLY )
 
-  # Generate and install the Package1Config.cmake file
+  # Generate and install the Package1Config.cmake file for the install tree
   install(EXPORT ${PROJECT_NAME}
     DESTINATION ${CMAKE_INSTALL_LIBDIR}/cmake/${PROJECT_NAME}
     NAMESPACE ${PROJECT_NAME}::

tribits/examples/TribitsExampleProject2/packages/package1/src/CMakeLists.raw.cmake

@@ -7,8 +7,7 @@ target_link_libraries(Package1_package1
 set_target_properties(Package1_package1 PROPERTIES
   EXPORT_NAME package1)
 add_library(Package1::package1 ALIAS Package1_package1)
-install(
-  TARGETS Package1_package1
+install(TARGETS Package1_package1
   EXPORT ${PROJECT_NAME}
   INCLUDES DESTINATION ${CMAKE_INSTALL_INCLUDEDIR} )
 install(