Defined Py_BUILD_CORE_MODULE also on VC6.
diff --git a/PC/VC6/_multiprocessing.dsp b/PC/VC6/_multiprocessing.dsp
index 2d3d637..2dcaf83 100644
--- a/PC/VC6/_multiprocessing.dsp
+++ b/PC/VC6/_multiprocessing.dsp
@@ -43,8 +43,8 @@
# PROP Ignore_Export_Lib 0
# PROP Target_Dir ""
F90=df.exe
-# ADD BASE CPP /nologo /MT /W3 /GX /O2 /D "WIN32" /D "NDEBUG" /D "_WINDOWS" /YX /FD /c
-# ADD CPP /nologo /MD /W3 /GX /Zi /O2 /I "..\..\Include" /I ".." /D "NDEBUG" /D "WIN32" /D "_WINDOWS" /YX /FD /c
+# ADD BASE CPP /nologo /MT /W3 /GX /O2 /D "Py_BUILD_CORE_MODULE" /D "WIN32" /D "NDEBUG" /D "_WINDOWS" /YX /FD /c
+# ADD CPP /nologo /MD /W3 /GX /Zi /O2 /I "..\..\Include" /I ".." /D "Py_BUILD_CORE_MODULE" /D "NDEBUG" /D "WIN32" /D "_WINDOWS" /YX /FD /c
# ADD BASE MTL /nologo /D "NDEBUG" /mktyplib203 /o "NUL" /win32
# ADD MTL /nologo /D "NDEBUG" /mktyplib203 /o "NUL" /win32
# ADD BASE RSC /l 0x409 /d "NDEBUG"
@@ -71,8 +71,8 @@
# PROP Ignore_Export_Lib 0
# PROP Target_Dir ""
F90=df.exe
-# ADD BASE CPP /nologo /MTd /W3 /Gm /GX /Zi /Od /D "WIN32" /D "_DEBUG" /D "_WINDOWS" /YX /FD /c
-# ADD CPP /nologo /MDd /W3 /Gm /GX /Zi /Od /I "..\..\Include" /I ".." /D "_DEBUG" /D "WIN32" /D "_WINDOWS" /YX /FD /c
+# ADD BASE CPP /nologo /MTd /W3 /Gm /GX /Zi /Od /D "Py_BUILD_CORE_MODULE" /D "WIN32" /D "_DEBUG" /D "_WINDOWS" /YX /FD /c
+# ADD CPP /nologo /MDd /W3 /Gm /GX /Zi /Od /I "..\..\Include" /I ".." /D "Py_BUILD_CORE_MODULE" /D "_DEBUG" /D "WIN32" /D "_WINDOWS" /YX /FD /c
# ADD BASE MTL /nologo /D "_DEBUG" /mktyplib203 /o "NUL" /win32
# ADD MTL /nologo /D "_DEBUG" /mktyplib203 /o "NUL" /win32
# ADD BASE RSC /l 0x409 /d "_DEBUG"