Fix spelling in elfSharedLibData
Summary: `__x86__64__` is unlikely to ever be defined. :)
#define DT_GNU_HASH 0x6ffffef5 /* GNU-style hash table. */
-#if defined(__x86__64__) || defined(__aarch64__)
+#if defined(__x86_64__) || defined(__aarch64__)
# define ELF_RELOC_TYPE ELF64_R_TYPE
# define ELF_RELOC_SYM ELF64_R_SYM
#else
