[llvm] [Flang] explicitly link the pthread library when building shared flang-rt. (PR #129956)

[Daniel Chen via llvm-commits]

================
@@ -142,6 +142,8 @@ function (add_flangrt_library name)
   endif ()
   if (build_shared)
     add_library("${name_shared}" SHARED ${extra_args} ${ARG_ADDITIONAL_HEADERS} ${ARG_UNPARSED_ARGUMENTS})
+    find_package(Threads REQUIRED)
----------------
DanielCChen wrote:

Sure. Will do.

https://github.com/llvm/llvm-project/pull/129956