x86/asm: move user code selector values to common

I'll need them in parasite head and in exit.

travis-ci: success for Rectify 32-bit compatible C/R on x86
Signed-off-by: Dmitry Safonov <dsafonov@virtuozzo.com>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>
Signed-off-by: Andrei Vagin <avagin@virtuozzo.com>

criu/arch/x86/call32.S

@@ -18,9 +18,6 @@
 
 #include "common/asm/linkage.h"
 
-#define __USER32_CS	0x23
-#define __USER_CS	0x33
-
 	.text
 
 /*

include/common/arch/x86/asm/linkage.h

@@ -21,4 +21,7 @@
 
 #endif  /* __ASSEMBLY__ */
 
+#define __USER32_CS	0x23
+#define __USER_CS	0x33
+
 #endif /* __CR_LINKAGE_H__ */