linux-user, configure: fix (again) syscall_nr.h dependencies cleanup

This patch fixes two problems:
- it cleanups linux-user variants (for instance ppc64-linux-user
  and ppc64le-linux-user)
- it removes the .o file when it removes the .d file, otherwise the .o
  file is never updated

Fixes: 5f29856b85 ("linux-user, configure: improve syscall_nr.h dependencies checking")
Fixes: 4d6a835dea ("linux-user: introduce parameters to generate syscall_nr.h")
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20200325075757.1959961-1-laurent@vivier.eu>

configure

@@ -1910,9 +1910,11 @@ for arch in alpha hppa m68k xtensa sh4 microblaze arm ppc s390x sparc sparc64 \
     # remove the file if it has been generated in the source directory
     rm -f "${source_path}/linux-user/${arch}/syscall_nr.h"
     # remove the dependency files
-    test -d ${arch}-linux-user && find ${arch}-linux-user -type f -name "*.d" \
-         -exec grep -q "${source_path}/linux-user/${arch}/syscall_nr.h" {} \; \
-         -exec rm {} \;
+    for target in ${arch}*-linux-user ; do
+        test -d "${target}" && find "${target}" -type f -name "*.d" \
+             -exec grep -q "${source_path}/linux-user/${arch}/syscall_nr.h" {} \; \
+             -print | while read file ; do rm "${file}" "${file%.d}.o" ; done
+    done
 done
 
 if test -z "$python"