Fix example clang link flags

Author: miloyip

example/CMakeLists.txt

@@ -22,7 +22,8 @@ add_definitions(-D__STDC_FORMAT_MACROS)
 if ("${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU")
     set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -pthread -Werror -Wall -Wextra -Weffc++ -Wswitch-default")
 elseif (CMAKE_CXX_COMPILER_ID MATCHES "Clang")
-    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -lpthread -Werror -Wall -Wextra -Weffc++ -Wswitch-default -Wfloat-equal -Wimplicit-fallthrough -Weverything")
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Werror -Wall -Wextra -Weffc++ -Wswitch-default -Wfloat-equal -Wimplicit-fallthrough -Weverything")
+    set(CMAKE_LINK_FLAGS "${CMAKE_LINK_FLAGS} -lpthread")
 elseif ("${CMAKE_CXX_COMPILER_ID}" STREQUAL "MSVC")
     add_definitions(-D_CRT_SECURE_NO_WARNINGS=1)
 endif()