Merge i386 and x86_64 back ends into a general x86

The reason being that x86_64 needs to handle i386 anyway, and keeping the
two together might reduce code duplicity.
diff --git a/ltrace-elf.c b/ltrace-elf.c
index 9b6cf6b..99d06d6 100644
--- a/ltrace-elf.c
+++ b/ltrace-elf.c
@@ -273,8 +273,11 @@
 		exit(EXIT_FAILURE);
 	}
 
-	if ((lte->ehdr.e_ident[EI_CLASS] != LT_ELFCLASS
-	     || lte->ehdr.e_machine != LT_ELF_MACHINE)
+	if (1
+#ifdef LT_ELF_MACHINE
+	    && (lte->ehdr.e_ident[EI_CLASS] != LT_ELFCLASS
+		|| lte->ehdr.e_machine != LT_ELF_MACHINE)
+#endif
 #ifdef LT_ELF_MACHINE2
 	    && (lte->ehdr.e_ident[EI_CLASS] != LT_ELFCLASS2
 		|| lte->ehdr.e_machine != LT_ELF_MACHINE2)