BuildSystem: Rework the whole cmake build system

Now files are installed using the install() command instead of manually
copying files to their destinations. This allows automatic recompilation
of headers that did not work previously

userspace/libraries/LibELF/CMakeLists.txt

@@ -1,12 +1,8 @@
-cmake_minimum_required(VERSION 3.26)
-
-project(LibELF CXX)
-
-add_custom_target(libelf-headers
-	COMMAND ${CMAKE_COMMAND} -E copy_directory_if_different ${CMAKE_CURRENT_SOURCE_DIR}/include/ ${BANAN_INCLUDE}/
-	DEPENDS sysroot
+set(SOURCES
+	dummy.cpp
 )
 
-add_custom_target(libelf-install
-	DEPENDS libelf-headers
-)
+add_library(libelf ${SOURCES})
+
+banan_install_headers(libelf)
+install(TARGETS libelf)