Do not define CONFIGURE_DEPENDS for library usage

[BenjaminBeichler]

If you include CLI11 in projects, it is a bit confusing, that it uses CONFIGURE_DEPENDS in its globbing, as normally the user do not add files to libraries. I would suggest adding the idiomatic check IF (CMAKE_PROJECT_NAME STREQUAL PROJECT_NAME) before the for-loop, to only "reglob", if this is the main project.

CLI11/CMakeLists.txt

Lines 157 to 163 in 4d34311

	# To see in IDE, headers must be listed for target
	set(header-patterns "${PROJECT_SOURCE_DIR}/include/CLI/*")
	if(NOT CMAKE_VERSION VERSION_LESS 3.12)
	list(INSERT header-patterns 0 CONFIGURE_DEPENDS)
	endif()
	file(GLOB CLI11_headers ${header-patterns})