linux-user: Fix pipe syscall return for SPARC

SPARC is one of the CPUs which has a funny syscall ABI for the
pipe syscall; add it to the set of special cases in do_pipe().

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Riku Voipio <riku.voipio@linaro.org>

linux-user/syscall.c

@@ -1032,6 +1032,9 @@ static abi_long do_pipe(void *cpu_env, abi_ulong pipedes,
 #elif defined(TARGET_SH4)
         ((CPUSH4State*)cpu_env)->gregs[1] = host_pipe[1];
         return host_pipe[0];
+#elif defined(TARGET_SPARC)
+        ((CPUSPARCState*)cpu_env)->regwptr[1] = host_pipe[1];
+        return host_pipe[0];
 #endif
     }