Makefile.defs: version set to 4.0.0-rc0

- branch for release series 4.0.x has been created

Makefile.defs

@@ -162,7 +162,7 @@ INSTALL_FLAVOUR=$(FLAVOUR)
 VERSION = 4
 PATCHLEVEL = 0
 SUBLEVEL =  0
-EXTRAVERSION = -pre2
+EXTRAVERSION = -rc0
 
 # memory manager switcher
 # 0 - f_malloc (fast malloc)