Merge pull request swiftlang#828 from compnerd/pthread

build: android bundles pthread into libc

Author: compnerd

CMakeLists.txt

@@ -112,6 +112,9 @@ set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR})
 
 set(CMAKE_THREAD_PREFER_PTHREAD TRUE)
 set(THREADS_PREFER_PTHREAD_FLAG TRUE)
+if(ANDROID)
+  set(CMAKE_HAVE_LIBC_PTHREAD YES)
+endif()
 find_package(Threads REQUIRED)
 
 include(CheckCCompilerFlag)