CMake: add object libraries to the export set for static builds

The dependencies' object files are combined into a single library file.
For static libraries, the usage flags (include directories, compile
definitions) are copied by reference rather than by value so the object
libraries are needed in the export set.

Author: tstenner

CMakeLists.txt

@@ -114,7 +114,7 @@ if(LSL_BUNDLED_PUGIXML)
 	message(STATUS "Using bundled pugixml")
 	target_sources(lslobj PRIVATE thirdparty/pugixml/pugixml.cpp)
 	target_include_directories(lslobj SYSTEM PUBLIC
-		${CMAKE_CURRENT_SOURCE_DIR}/thirdparty/pugixml)
+		$<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/thirdparty/pugixml>)
 else()
 	message(STATUS "Using system pugixml")
 	find_package(pugixml REQUIRED)
@@ -178,7 +178,7 @@ target_compile_definitions(lslboost
 		BOOST_THREAD_DONT_PROVIDE_INTERRUPTIONS
 )
 target_include_directories(lslboost SYSTEM PUBLIC
-	${CMAKE_CURRENT_SOURCE_DIR}/lslboost)
+	$<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/lslboost>)
 
 # target configuration for the internal lslobj target
 target_link_libraries(lslobj PRIVATE lslboost)
@@ -273,7 +273,12 @@ write_basic_package_version_file(
 	COMPATIBILITY AnyNewerVersion
 )
 
-install(TARGETS lsl
+set(LSLTargets lsl)
+if(LSL_BUILD_STATIC)
+	list(APPEND LSLTargets lslobj lslboost)
+endif()
+
+install(TARGETS ${LSLTargets}
 	EXPORT LSLTargets
 	COMPONENT liblsl
 	RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR}