including lmpwindows.h globally from lmptype.h does more harm than good

this addresses some (cross) compilation issues locally.
in the long run, this should be addressed by implementing issue #1884
where platform specific functionality is wrapped into a small library
of generic functions adapted for LAMMPS' needs (like utils:: does for
non-portable convenience functions).

src/timer.cpp

@@ -21,6 +21,9 @@
 #include <cstring>
 
 #ifdef _WIN32
+#ifndef WIN32_LEAN_AND_MEAN
+#define WIN32_LEAN_AND_MEAN
+#endif
 #include <windows.h>
 #include <cstdint>
 #else