target/xtensa/xtensa-semi: Fix compilation problem on Haiku

target/xtensa/xtensa-semi: Fix compilation problem on Haiku

The errno numbers are very large on Haiku, so the linking currently
fails there with a "final link failed: memory exhausted" error
message. We should not use the errno number as array indexes here,
thus convert the code to a switch-case statement instead. A clever
compiler should be able to optimize this code in a similar way
anway.

Reported-by: Richard Zak <richard.j.zak@gmail.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Acked-by: Max Filippov <jcmvbkbc@gmail.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20210706081822.1316551-1-thuth@redhat.com>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>