Makefile.defs: version set to 5.3.0-dev8

- end of development for v5.3.x

src/Makefile.defs

@@ -107,7 +107,7 @@ INSTALL_FLAVOUR=$(FLAVOUR)
 VERSION = 5
 PATCHLEVEL = 3
 SUBLEVEL =  0
-EXTRAVERSION = -dev7
+EXTRAVERSION = -dev8
 
 # memory manager switcher
 # 0 - f_malloc (fast malloc)