File 3013-riscv64-link-pthread.patch of Package ceph-ceph-18.2.7

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 9fbab8d..98ccf58 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -30,6 +30,7 @@ endif()
 
 if(CMAKE_SYSTEM_NAME MATCHES "Linux")
   set(LINUX ON)
+  set(THREADS_PREFER_PTHREAD_FLAG ON)
   FIND_PACKAGE(Threads)
 elseif(CMAKE_SYSTEM_NAME MATCHES "FreeBSD")
   set(FREEBSD ON)