Added 2 new XT machines

Implemented the American XT computer and the Iskra 3104(A clone made in Belarusian SSR). Also removed the Goldstar 386 & the Unknown Headland 386SX board as they were very buggy and their purpose is now served by the much better Intel 82335 boards.

src/win/Makefile.mingw

@@ -39,9 +39,6 @@ ifeq ($(DEV_BUILD), y)
  ifndef AMD_K5
   AMD_K5	:= y
  endif
- ifndef AMI386X
-  AMI386SX	:= y
- endif
  ifndef CL5422
   CL5422	:= y
  endif
@@ -121,9 +118,6 @@ else
  ifndef AMD_K5
   AMD_K5	:= n
  endif
- ifndef AMI386SX
-  AMI386SX	:= n
- endif
  ifndef CL5422
   CL5422	:= n
  endif
@@ -509,10 +503,6 @@ ifeq ($(AMD_K5), y)
 OPTS		+= -DUSE_AMD_K5
 endif
 
-ifeq ($(AMI386SX), y)
-OPTS		+= -DUSE_AMI386SX
-endif
-
 ifeq ($(CL5422), y)
 OPTS		+= -DUSE_CL5422
 endif