Remove tls.h inclusion from internal errno.h

The tls.h inclusion is not really required and limits possible
definition on more arch specific headers.

This is a cleanup to allow inline functions on sysdep.h, more
specifically on i386 and ia64 which requires to access some tls
definitions its own.

No semantic changes expected, checked with a build against all
affected ABIs.

sysdeps/unix/sysv/linux/sysdep.h

@@ -20,6 +20,7 @@
 
 #include <bits/wordsize.h>
 #include <kernel-features.h>
+#include <endian.h>
 #include <errno.h>
 
 #undef INTERNAL_SYSCALL_ERROR_P