fix and enable i386 support

This gives ~5K size reduction with bc3.1.
Today no one uses pre-i386 CPUs so there is no good
reason against having an extra optimization.

config.b

@@ -105,9 +105,9 @@ set XUPX=upx --8086 --best
 :* select your default target: required CPU and what FAT system to support
 :**********************************************************************
 
-set XCPU=86
+:- set XCPU=86
 :- set XCPU=186
-:- set XCPU=386
+set XCPU=386
 
 :- set XFAT=16
 set XFAT=32

config.m

@@ -52,9 +52,9 @@ XUPX=upx --8086 --best
 # select your default target: required CPU and what FAT system to support
 #*********************************************************************
 
-XCPU=86
+# XCPU=86
 # XCPU=186
-# XCPU=386
+XCPU=386
 
 # XFAT=16
 XFAT=32

mkfiles/generic.mak

@@ -9,9 +9,11 @@ TARGETOPT=-1-
 
 !if $(XCPU) == 186
 TARGETOPT=-1
+ALLCFLAGS=$(ALLCFLAGS) -DI186
 !endif
 !if $(XCPU) == 386
 TARGETOPT=-3
+ALLCFLAGS=$(ALLCFLAGS) -DI386
 !endif
 
 !if $(XFAT) == 32