PATCH:bksys - added mingw as win32 platform

[Ralf Habacker]

Hi all, 

here is another patch for bksys. Any objectivities against submitting ? (I 
have an svn write access) 

Regards 


ChangeLog: 
added mingw as win32 platform  

--- bksys/generic.py	(revision 464504)
+++ bksys/generic.py	(working copy)
@@ -413,8 +413,8 @@
 	## i see what it does now - however importing default tools causes 
performance issues (TODO ita)
 	from SCons.Tool import Tool;
 	Tool('default').generate(env)
-
-	if env['PLATFORM'] in ('cygwin', 'win32', 'win64'):
+	
+	if env['PLATFORM'] in ('cygwin', 'mingw', 'win32', 'win64'):
 		env['WINDOWS']=1
 	else:
 		env['WINDOWS']=0