target/arm: Only include tcg/oversized-guest.h if CONFIG_TCG

Fixes the build for --disable-tcg.

This header is only needed for cross-hosting.  Without CONFIG_TCG,
we know this is an AArch64 host, CONFIG_ATOMIC64 will be set, and
the TCG_OVERSIZED_GUEST block will never be compiled.

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
diff --git a/target/arm/ptw.c b/target/arm/ptw.c
index b2dc223..37bcb17 100644
--- a/target/arm/ptw.c
+++ b/target/arm/ptw.c
@@ -14,8 +14,9 @@
 #include "cpu.h"
 #include "internals.h"
 #include "idau.h"
-#include "tcg/oversized-guest.h"
-
+#ifdef CONFIG_TCG
+# include "tcg/oversized-guest.h"
+#endif
 
 typedef struct S1Translate {
     ARMMMUIdx in_mmu_idx;