linux_user: elfload: Default ELF_MACHINE to ELF_ARCH

In most (but not all) cases, ELF_MACHINE and ELF_ARCH are safely the
same. Default ELF_MACHINE to ELF_ARCH. This makes defining ELF_MACHINE
optional for target-*/cpu.h when they are known to match.
Reviewed-by: NRichard Henderson <rth@twiddle.net>
Acked-By: NRiku Voipio <riku.voipio@linaro.org>
Signed-off-by: NPeter Crosthwaite <crosthwaite.peter@gmail.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

linux-user/elfload.c

@@ -1245,6 +1245,10 @@ static inline void init_thread(struct target_pt_regs *regs,
 #define ELF_PLATFORM (NULL)
 #endif
 
+#ifndef ELF_MACHINE
+#define ELF_MACHINE ELF_ARCH
+#endif
+
 #ifndef ELF_HWCAP
 #define ELF_HWCAP 0
 #endif