Fix visibility of check_sse2 symbol; DDLEXPORT doesn't work in gas source

vm/cpu-x86.32.S

@@ -51,3 +51,8 @@ DEF(bool,check_sse2,(void)):
 	ret
 
 #include "cpu-x86.S"
+
+#ifdef WINDOWS
+	.section .drectve
+	.ascii " -export:check_sse2"
+#endif

vm/cpu-x86.32.h

@@ -4,5 +4,3 @@ register CELL ds asm("esi");
 register CELL rs asm("edi");
 
 #define F_FASTCALL __attribute__ ((regparm (2)))
-
-DLLEXPORT bool check_sse2(void);