target/xtensa: add two missing headers to core import script

Include qemu/osdep.h and qemu-common.h at the beginning of imported
xtensa core source file.
Signed-off-by: NMax Filippov <jcmvbkbc@gmail.com>

target/xtensa/import_core.sh

@@ -25,9 +25,11 @@ tar -xf "$OVERLAY" -O gdb/xtensa-config.c | \
     sed -n '1,/*\//p;/XTREG/,/XTREG_END/p' > "$TARGET"/gdb-config.c
 
 cat <<EOF > "${TARGET}.c"
+#include "qemu/osdep.h"
 #include "cpu.h"
 #include "exec/exec-all.h"
 #include "exec/gdbstub.h"
+#include "qemu-common.h"
 #include "qemu/host-utils.h"
 
 #include "core-$NAME/core-isa.h"