fix(util): compilation problems when using msys2

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>

src/util/lean_path.cpp

@@ -4,6 +4,9 @@ Released under Apache 2.0 license as described in the file LICENSE.
 
 Author: Leonardo de Moura
 */
+#if defined(LEAN_WINDOWS) && !defined(LEAN_CYGWIN)
+#include <windows.h>
+#endif
 #include <string>
 #include <cstdlib>
 #include <fstream>
@@ -37,7 +40,6 @@ bool is_directory(char const * pathname) {
 
 #if defined(LEAN_WINDOWS) && !defined(LEAN_CYGWIN)
 // Windows version
-#include <windows.h>
 static char g_path_sep     = ';';
 static char g_sep          = '\\';
 static char g_bad_sep      = '/';

src/util/thread.h

@@ -41,6 +41,7 @@ namespace this_thread = std::this_thread;
 #else
 // MULTI THREADING SUPPORT BASED ON THE BOOST LIBRARY
 #include <boost/thread.hpp>
+#include <boost/atomic.hpp>
 #define LEAN_THREAD_LOCAL thread_local
 namespace lean {
 void set_thread_stack_size(size_t );