Fixed thread-safety

Fixed huge mistake in Clock code (Allocating a mutex everytime instead
of locking it)
HashDigest and StringStream class are no longer thread-safe (That was
stupid anyway)


Former-commit-id: d07a6859df27eac2c5171e75720b3963b6a5fbbb

src/Nazara/Core/Log.cpp

@@ -11,7 +11,13 @@
 #include <cstring>
 
 #if NAZARA_CORE_DUPLICATE_LOG_TO_COUT
-#include <cstdio>
+	#include <cstdio>
+#endif
+
+#if NAZARA_CORE_THREADSAFE && NAZARA_THREADSAFETY_LOG
+	#include <Nazara/Core/ThreadSafety.hpp>
+#else
+	#include <Nazara/Core/ThreadSafetyOff.hpp>
 #endif
 
 #include <Nazara/Core/Debug.hpp>
@@ -116,7 +122,7 @@ void NzLog::Write(const NzString& string)
 		if (m_writeTime)
 		{
 			line.Reserve(23 + string.GetSize() + 1);
-			line.Resize(23);
+			line.Set(23, '\0'); // Buffer non-initialisé
 
 			time_t currentTime = std::time(nullptr);
 			std::strftime(&line[0], 24, "%d/%m/%Y - %H:%M:%S: ", std::localtime(&currentTime));