From 8b5e85a95c9395dee8af807aed4efc8ba9fed2d2 Mon Sep 17 00:00:00 2001
From: Niels Grewe <niels.grewe@halbordnung.de>
Date: Fri, 9 Oct 2015 09:47:55 +0000
Subject: [PATCH] Set the -pthread compiler flag when pthreads is used.

Apparently, setting -lpthread is not enough to convince gcc to actually
link a thread library, so if we are using pthreads, set the -pthread
flag as well. It fixes the gcc situation and doesn't have any adverse
effects for clang either.
---
 CMakeLists.txt | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 4b4f37a..26d82a8 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -240,7 +240,9 @@ endif (ENABLE_OBJCXX)
 set(CMAKE_THREAD_PREFER_PTHREAD)
 include(FindThreads)
 set(objc_LINK_FLAGS "${objc_LINK_FLAGS} ${CMAKE_THREAD_LIBS_INIT}")
-
+if(CMAKE_USE_PTHREADS_INIT)
+  set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -pthread")
+endif()
 
 
 add_library(objc SHARED ${libobjc_C_SRCS} ${libobjc_ASM_SRCS} ${libobjc_OBJC_SRCS} ${libobjc_CXX_SRCS})