THRIFT-3321 Thrift can't be added as a subdirectory of another CMake-based project

Patch: Frane Šarić
diff --git a/build/cmake/CPackConfig.cmake b/build/cmake/CPackConfig.cmake
index 0240005..45077c0 100644
--- a/build/cmake/CPackConfig.cmake
+++ b/build/cmake/CPackConfig.cmake
@@ -28,8 +28,8 @@
 set(CPACK_PACKAGE_NAME "thrift")
 set(CPACK_PACKAGE_VERSION "${PACKAGE_VERSION}")
 set(CPACK_PACKAGE_DESCRIPTION_SUMMARY "Apache Thrift")
-set(CPACK_PACKAGE_DESCRIPTION_FILE "${CMAKE_SOURCE_DIR}/README.md")
-set(CPACK_RESOURCE_FILE_LICENSE "${CMAKE_SOURCE_DIR}/LICENSE")
+set(CPACK_PACKAGE_DESCRIPTION_FILE "${CMAKE_CURRENT_SOURCE_DIR}/README.md")
+set(CPACK_RESOURCE_FILE_LICENSE "${CMAKE_CURRENT_SOURCE_DIR}/LICENSE")
 set(CPACK_PACKAGE_VENDOR "Apache Software Foundation")
 set(CPACK_PACKAGE_CONTACT "dev@thrift.apache.org")
 set(CPACK_PACKAGE_INSTALL_DIRECTORY "${CPACK_PACKAGE_NAME}")