Refactor common PThreads CMake code

Move the flags and find of Threads to root CMakeLists.txt, rather
than duplicate these everywhere. Make explicit linking of library with
PThreads use the same mechanism.

Signed-off-by: Paul Elliott <paul.elliott@arm.com>

programs/aes/CMakeLists.txt

@@ -1,7 +1,3 @@
-set(CMAKE_THREAD_PREFER_PTHREAD TRUE)
-set(THREADS_PREFER_PTHREAD_FLAG TRUE)
-find_package(Threads)
-
 set(executables
     crypt_and_hash
 )

programs/cipher/CMakeLists.txt

@@ -1,7 +1,3 @@
-set(CMAKE_THREAD_PREFER_PTHREAD TRUE)
-set(THREADS_PREFER_PTHREAD_FLAG TRUE)
-find_package(Threads)
-
 set(executables
     cipher_aead_demo
 )

programs/fuzz/CMakeLists.txt

@@ -1,7 +1,3 @@
-set(CMAKE_THREAD_PREFER_PTHREAD TRUE)
-set(THREADS_PREFER_PTHREAD_FLAG TRUE)
-find_package(Threads)
-
 set(libs
     ${mbedtls_target}
     ${CMAKE_THREAD_LIBS_INIT}

programs/hash/CMakeLists.txt

@@ -1,7 +1,3 @@
-set(CMAKE_THREAD_PREFER_PTHREAD TRUE)
-set(THREADS_PREFER_PTHREAD_FLAG TRUE)
-find_package(Threads)
-
 set(executables
     generic_sum
     hello

programs/pkey/CMakeLists.txt

@@ -1,7 +1,3 @@
-set(CMAKE_THREAD_PREFER_PTHREAD TRUE)
-set(THREADS_PREFER_PTHREAD_FLAG TRUE)
-find_package(Threads)
-
 set(executables_mbedtls
     dh_client
     dh_server

programs/psa/CMakeLists.txt

@@ -1,7 +1,3 @@
-set(CMAKE_THREAD_PREFER_PTHREAD TRUE)
-set(THREADS_PREFER_PTHREAD_FLAG TRUE)
-find_package(Threads)
-
 set(executables
     aead_demo
     crypto_examples

programs/random/CMakeLists.txt

@@ -1,7 +1,3 @@
-set(CMAKE_THREAD_PREFER_PTHREAD TRUE)
-set(THREADS_PREFER_PTHREAD_FLAG TRUE)
-find_package(Threads)
-
 set(executables
     gen_entropy
     gen_random_ctr_drbg

programs/ssl/CMakeLists.txt

@@ -1,6 +1,3 @@
-set(THREADS_USE_PTHREADS_WIN32 true)
-set(CMAKE_THREAD_PREFER_PTHREAD TRUE)
-set(THREADS_PREFER_PTHREAD_FLAG TRUE)
 find_package(Threads)
 
 set(libs

programs/test/CMakeLists.txt

@@ -1,7 +1,3 @@
-set(CMAKE_THREAD_PREFER_PTHREAD TRUE)
-set(THREADS_PREFER_PTHREAD_FLAG TRUE)
-find_package(Threads)
-
 set(libs
     ${mbedtls_target}
 )

programs/test/cmake_subproject/CMakeLists.txt

@@ -1,9 +1,5 @@
 cmake_minimum_required(VERSION 3.5.1)
 
-set(CMAKE_THREAD_PREFER_PTHREAD TRUE)
-set(THREADS_PREFER_PTHREAD_FLAG TRUE)
-find_package(Threads)
-
 # Test the target renaming support by adding a prefix to the targets built
 set(MBEDTLS_TARGET_PREFIX subproject_test_)
 

programs/util/CMakeLists.txt

@@ -1,7 +1,3 @@
-set(CMAKE_THREAD_PREFER_PTHREAD TRUE)
-set(THREADS_PREFER_PTHREAD_FLAG TRUE)
-find_package(Threads)
-
 set(libs
     ${mbedcrypto_target}
 )

programs/x509/CMakeLists.txt

@@ -1,7 +1,3 @@
-set(CMAKE_THREAD_PREFER_PTHREAD TRUE)
-set(THREADS_PREFER_PTHREAD_FLAG TRUE)
-find_package(Threads)
-
 set(libs
     ${mbedx509_target}
 )