linux-user/mips64: Support o32 ABI syscalls

o32 ABI syscalls start at offset 4000.

Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Message-Id: <20201119161710.1985083-3-f4bug@amsat.org>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>

linux-user/mips64/syscall_nr.h

@@ -1,4 +1,7 @@
-#ifdef TARGET_ABI_MIPSN32
+#if defined(TARGET_ABI_MIPSO32)
+#define TARGET_SYSCALL_OFFSET 4000
+#include "syscall_o32_nr.h"
+#elif defined(TARGET_ABI_MIPSN32)
 #define TARGET_SYSCALL_OFFSET 6000
 #include "syscall_n32_nr.h"
 #else