Remove 32-bit assumptions from the ELF code.

Change-Id: I2c1f3d34c33685799aade8866eec44479ff9f963
diff --git a/libc/include/elf.h b/libc/include/elf.h
index ac0f1d2..285eb7d 100644
--- a/libc/include/elf.h
+++ b/libc/include/elf.h
@@ -46,5 +46,10 @@
   } a_un;
 } Elf64_auxv_t;
 
-#endif /* _ELF_H */
+#ifdef __LP64__
+#  define Elf_auxv_t Elf64_auxv_t
+#else
+#  define Elf_auxv_t Elf32_auxv_t
+#endif
 
+#endif /* _ELF_H */