From Axel and Philippe: define CPPPREP

git-svn-id: http://root.cern.ch/svn/root/trunk@15427 27541ba8-7e3a-0410-8455-c3a389f83636

config/Makefile.win32

@@ -70,6 +70,7 @@ NOOPT         =
 # Compiler:
 CXX           = cl
 CC            = cl
+CPPPREP       = cl -E -C -nologo
 CXXFLAGS      = -nologo -FIw32pragma.h \
                 $(BLDCXXFLAGS) $(EXTRA_CXXFLAGS)
 CXXOUT        = -Fo