Include the header files in case of installation.

include/CMakeLists.txt

@@ -0,0 +1,3 @@
+project(headers C)
+
+add_subdirectory(dmmlib)

include/dmmlib/CMakeLists.txt

@@ -0,0 +1,13 @@
+project(dmmlib-headers C)
+
+set(dmmlib_HDRS
+	dmmlib.h
+	heap.h
+)
+
+install(
+  FILES
+    ${dmmlib_HDRS}
+  DESTINATION
+    ${INCLUDE_INSTALL_DIR}/${APPLICATION_NAME}
+)