pthread: Added support for pthread condition variables

This is required for std::condition_variable support

Signed-off-by: Amey Inamdar <amey.inamdar@gmail.com>

components/pthread/test/test_cxx_cond_var.cpp

@@ -0,0 +1,48 @@
+#include <iostream>
+#include <thread>
+#include <condition_variable>
+#include <chrono>
+#include <mutex>
+#include <atomic>
+#include "unity.h"
+
+#if __GTHREADS && __GTHREADS_CXX0X
+
+std::condition_variable cv;
+std::mutex cv_m;
+std::atomic<int> i{0};
+
+static void waits(int idx, int timeout_ms)
+{
+    std::unique_lock<std::mutex> lk(cv_m);
+    auto now = std::chrono::system_clock::now();
+
+    if(cv.wait_until(lk, now + std::chrono::milliseconds(timeout_ms), [](){return i == 1;}))
+        std::cout << "Thread " << idx << " finished waiting. i == " << i << '\n';
+    else
+        std::cout << "Thread " << idx << " timed out. i == " << i << '\n';
+}
+
+static void signals(int signal_ms)
+{
+    std::this_thread::sleep_for(std::chrono::milliseconds(signal_ms));
+    std::cout << "Notifying...\n";
+    cv.notify_all();
+    std::this_thread::sleep_for(std::chrono::milliseconds(signal_ms));
+    i = 1;
+    std::cout << "Notifying again...\n";
+    cv.notify_all();
+}
+
+TEST_CASE("C++ condition_variable", "[std::condition_variable]")
+{
+    i = 0;
+    std::thread t1(waits, 1, 100), t2(waits, 2, 800), t3(signals, 200);
+
+    t1.join();
+    t2.join();
+    t3.join();
+
+    std::cout << "All threads joined\n";
+}
+#endif