[skip ci] [Mesh] add comment for boost

src/Mod/MeshPart/App/MeshFlatteningBoostPython.cpp

@@ -31,6 +31,8 @@
 # include <TopoDS_Face.hxx>
 #endif
 
+// boost is purposely not in the precompiled headers, see
+// https://github.com/FreeCAD/FreeCAD/pull/7979#issuecomment-1358123252
 #include <boost/python.hpp>
 #include <boost/python/call.hpp>
 #include <boost/python/class.hpp>

src/boost_regex.hpp

@@ -3,17 +3,16 @@
 
 #include <boost/version.hpp>
 
-#if BOOST_VERSION >= 107800
-
 // Workaround for boost >= 1.78
-#ifdef WIN32
-#ifndef NOMINMAX
-#define NOMINMAX
-#endif
-#include <Windows.h>
+#if BOOST_VERSION >= 107800
+# ifdef WIN32
+#  ifndef NOMINMAX
+#   define NOMINMAX
+#  endif
+#  include <Windows.h>
+# endif
 #endif
 
-#endif
 #include <boost/regex.hpp>
 
 #endif // #ifndef FREECAD_REGEX_HPP_WORKAROUND