musl: mips64: Swap order of si_errno and si_code in siginfo_t

All MIPS targets, 32-bit and 64-bit, swap these around.

See:
https://git.musl-libc.org/cgit/musl/tree/arch/mips64/bits/signal.h#n103
https://git.musl-libc.org/cgit/musl/tree/include/signal.h#n100

Signed-off-by: Jens Reidel <[email protected]>

(backport <#4530>)
(cherry picked from commit 76072a6)

Author: Gelbpunkt

src/unix/linux_like/linux/musl/mod.rs

@@ -157,10 +157,10 @@ s! {
     // FIXME(union): C implementation uses unions
     pub struct siginfo_t {
         pub si_signo: c_int,
-        #[cfg(not(target_arch = "mips"))]
+        #[cfg(not(any(target_arch = "mips", target_arch = "mips64")))]
         pub si_errno: c_int,
         pub si_code: c_int,
-        #[cfg(target_arch = "mips")]
+        #[cfg(any(target_arch = "mips", target_arch = "mips64"))]
         pub si_errno: c_int,
         #[doc(hidden)]
         #[deprecated(