add check for srpc-targets.cmake

srpc-config.cmake.in

@@ -5,7 +5,9 @@ set_and_check(SRPC_INCLUDE_DIR "@PACKAGE_CONFIG_INC_DIR@")
 set_and_check(SRPC_LIB_DIR "@PACKAGE_CONFIG_LIB_DIR@")
 set_and_check(SRPC_BIN_DIR "@PACKAGE_CONFIG_BIN_DIR@")
 
-include ("${CMAKE_CURRENT_LIST_DIR}/srpc-targets.cmake")
+if (EXISTS pathToFileOrDir)
+    include ("${CMAKE_CURRENT_LIST_DIR}/srpc-targets.cmake")
+endif ()
 
 check_required_components(srpc)