linux-user: Create special-errno.h

Pull the two internal errno used by qemu internally into their own
header file.  This includes the one define required by safe-syscall.S.

Reviewed-by: Warner Losh <imp@bsdimp.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

linux-user/cpu_loop-common.h

@@ -21,6 +21,7 @@
 #define CPU_LOOP_COMMON_H
 
 #include "exec/log.h"
+#include "special-errno.h"
 
 #define EXCP_DUMP(env, fmt, ...)                                        \
 do {                                                                    \