mips-linux-user: Cleanup sigframe format and checking

Given that we lock_user_struct at the beginning of setting up and
restoring a signal frame, none of the intervening __get/put_user
calls can ever fail.  So don't check them.

Delete dead code, and re-format as necessary for checkpatch.

Signed-off-by: Richard Henderson <rth@twiddle.net>
mips-linux-user: Save and restore fpu and dsp from sigcontext

Probably not required by anything I'm ever planning to test,
but why not?  It's certainly easy to fill in these blanks...

Signed-off-by: Richard Henderson <rth@twiddle.net>
mips-linux-user: Fix n32 and n64 syscalls

n32/n64 have different argument registers from o32.

In addition, use abi_long properly instead of the
host unsigned int for errno detection.

Signed-off-by: Richard Henderson <rth@twiddle.net>
mips64-linux-user: Enable 64-bit address mode and fpu

Signed-off-by: Richard Henderson <rth@twiddle.net>
target-mips: Fix check_cp1_64bitmode

COP1X refers to the availability of indexed memory operations,
not whether the FPU has 64-bit registers.

Signed-off-by: Richard Henderson <rth@twiddle.net>
mipsn32-linux-user: Restrict address space to 31-bits.

Just like o32, n32 will fail if we don't respect the 31-bit address limit.

Signed-off-by: Richard Henderson <rth@twiddle.net>
mipsn32-linux-user: Configure the architecture properly

N32 is a 64-bit cpu with a 32-bit address space.  We have
existing cpp defines for this situation, but weren't using them.

This does mean that the linux-user/mipsn32 directory must be
merged with the linux-user/mips64 directory, and differences
must be resolved via ifdefs.

Signed-off-by: Richard Henderson <rth@twiddle.net>