CMake: don't override target output locations if not top-level

CMake was unconditionally setting output locations globally, but
it should not do that if it is not the top-level project (e.g.
during chain building).  Detect this fact and only set the output
location when top level.

Fixes Issue: #708
Fix By: Anthony Alayo (@anthonyalayo)

CMakeLists.txt

@@ -99,11 +99,15 @@ IF (CARES_SYMBOL_HIDING)
 	ENDIF ()
 ENDIF ()
 
-# Keep build organized.
-SET (CMAKE_RUNTIME_OUTPUT_DIRECTORY "${PROJECT_BINARY_DIR}/${CMAKE_INSTALL_BINDIR}")
-SET (CMAKE_LIBRARY_OUTPUT_DIRECTORY "${PROJECT_BINARY_DIR}/${CMAKE_INSTALL_LIBDIR}")
-SET (CMAKE_ARCHIVE_OUTPUT_DIRECTORY "${PROJECT_BINARY_DIR}/${CMAKE_INSTALL_LIBDIR}")
-SET (PACKAGE_DIRECTORY ${PROJECT_BINARY_DIR}/package)
+# Keep build organized, but only if it is the top-level project.
+# CMake 3.21 or later has PROJECT_IS_TOP_LEVEL, but we aren't yet depending on
+# that version.
+IF (CMAKE_CURRENT_SOURCE_DIR STREQUAL CMAKE_SOURCE_DIR)
+	SET (CMAKE_RUNTIME_OUTPUT_DIRECTORY "${PROJECT_BINARY_DIR}/${CMAKE_INSTALL_BINDIR}")
+	SET (CMAKE_LIBRARY_OUTPUT_DIRECTORY "${PROJECT_BINARY_DIR}/${CMAKE_INSTALL_LIBDIR}")
+	SET (CMAKE_ARCHIVE_OUTPUT_DIRECTORY "${PROJECT_BINARY_DIR}/${CMAKE_INSTALL_LIBDIR}")
+	SET (PACKAGE_DIRECTORY ${PROJECT_BINARY_DIR}/package)
+ENDIF ()
 
 # Destinations for installing different kinds of targets (pass to install command).
 SET (TARGETS_INST_DEST