build UPDATE copy all public headers into a binary dir

... to allow standard include paths to work even
if the library is not installed.

Author: michalvasko

CMakeLists.txt

@@ -322,9 +322,10 @@ if ("${BUILD_TYPE_UPPER}" STREQUAL "DEBUG")
     source_format_enable(0.77)
 endif()
 
-# generate files
+# generate and copy all public header files
 configure_file(${PROJECT_SOURCE_DIR}/src/ly_config.h.in ${PROJECT_BINARY_DIR}/libyang/ly_config.h @ONLY)
 configure_file(${PROJECT_SOURCE_DIR}/src/version.h.in ${PROJECT_BINARY_DIR}/libyang/version.h @ONLY)
+file(COPY ${headers} DESTINATION ${PROJECT_BINARY_DIR}/libyang)
 
 # DOC-only target with no extra dependencies
 if("${BUILD_TYPE_UPPER}" STREQUAL "DOCONLY")