linux-user/mips64: Restore setup_frame() for o32 ABI

linux-user/mips64: Restore setup_frame() for o32 ABI

64-bit MIPS targets lost setup_frame() during the refactor in commit
8949bef18b9. Restore it declaring TARGET_ARCH_HAS_SETUP_FRAME, to be
able to build the o32 ABI target.

Fixes: 8949bef18b9 ("linux-user: move mips/mips64 signal.c parts to mips directory")
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: <20201119161710.1985083-2-f4bug@amsat.org>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>