linux-user: Check if RESOLVE_CACHED flag is defined before using it

openat2.h was introduced in Linux kernel 5.6. However, RESOLVE_CACHED
flag was only added in kernel 5.12 and later. Therefore, we need to check
if RESOLVE_CACHED flag is defined before using it.

Signed-off-by: Frank Chang <frank.chang@sifive.com>
Reviewed-by: Helge Deller <deller@gmx.de>
Signed-off-by: Helge Deller <deller@gmx.de>

linux-user/strace.c

@@ -1129,7 +1129,9 @@ UNUSED static const struct flags openat2_resolve_flags[] = {
     FLAG_GENERIC(RESOLVE_NO_SYMLINKS),
     FLAG_GENERIC(RESOLVE_BENEATH),
     FLAG_GENERIC(RESOLVE_IN_ROOT),
+#ifdef RESOLVE_CACHED
     FLAG_GENERIC(RESOLVE_CACHED),
+#endif
 #endif
     FLAG_END,
 };