cleanup: Move install targets to CMake files under export.

Since the install logic needs to install everything that is part of the
public interface of the project, it is arguable best put in the CMake
files of the `export` folder, which also contains the public code. This
also removes the necessity to include the subdirectories under `src` in
a particular order, which would otherwise exist due to the `install`
command needing to see all installed targets.

export/planloader/CMakeLists.txt

@@ -7,8 +7,21 @@ target_link_libraries(planloader substrait_io)
 
 install(
  TARGETS planloader
- LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR}
- PRIVATE_HEADER DESTINATION ${CMAKE_INSTALL_INCDIR})
+ substrait_io
+ substrait_common
+ substrait_proto
+ substrait_textplan_converter
+ substrait_textplan_loader
+ substrait_base_proto_visitor
+ symbol_table
+ error_listener
+ substrait_type
+ substrait_expression
+ textplan_grammar
+ EXPORT SubstraitTargets)
+install(FILES ../../include/substrait/common/Io.h
+ DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}/substrait/common")
+install(EXPORT SubstraitTargets DESTINATION lib/cmake/Substrait)
 
 if(${SUBSTRAIT_CPP_BUILD_TESTING})
  add_subdirectory(tests)

src/substrait/CMakeLists.txt

@@ -18,9 +18,9 @@ set(CMAKE_RUNTIME_OUTPUT_DIRECTORY
 set(ADDITIONAL_CLEAN_FILES
  "${CMAKE_ARCHIVE_OUTPUT_DIRECTORY};${CMAKE_RUNTIME_OUTPUT_DIRECTORY}")
 
+add_subdirectory(common)
 add_subdirectory(type)
 add_subdirectory(expression)
 add_subdirectory(function)
 add_subdirectory(proto)
 add_subdirectory(textplan)
-add_subdirectory(common)

src/substrait/common/CMakeLists.txt

@@ -24,24 +24,6 @@ if(${SUBSTRAIT_CPP_BUILD_TESTING})
  add_subdirectory(tests)
 endif()
 
-install(
- TARGETS substrait_io
- substrait_common
- substrait_proto
- substrait_textplan_converter
- substrait_textplan_loader
- substrait_base_proto_visitor
- symbol_table
- error_listener
- substrait_type
- substrait_expression
- textplan_grammar
- DESTINATION ${CMAKE_INSTALL_LIBDIR}
- EXPORT SubstraitTargets)
-install(FILES ../../../include/substrait/common/Io.h
- DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}/substrait/common")
-install(EXPORT SubstraitTargets DESTINATION lib/cmake/Substrait)
-
 add_executable(plantransformer PlanTransformerTool.cpp)
 
 target_link_libraries(plantransformer substrait_io)