Initialize the stack guard earlier when linking statically [BZ #7065]

The address of the stack canary is stored in a per-thread variable,
which means that we must ensure that the TLS area is intialized before
calling any -fstack-protector'ed functions.  For dynamically linked
applications, we ensure this (in a later patch) by disabling
-fstack-protector for the whole dynamic linker, but for static
applications, the AT_ENTRY address is called directly by the kernel, so
we must deal with the problem differently.

In static appliations, __libc_setup_tls performs the TCB setup and TLS
initialization, so this commit arranges for it to be called early and
unconditionally.  The call (and the stack guard initialization) is
before the DL_SYSDEP_OSCHECK hook, which if set will probably call
functions which are stack-protected (it does on Linux and NaCL too).  We
also move apply_irel up, so that we can still safely call functions that
require ifuncs while in __libc_setup_tls (though if stack-protection is
enabled we still have to avoid calling functions that are not
stack-protected at this stage).

nptl/nptl-init.c

@@ -70,10 +70,6 @@ int __have_futex_clock_realtime;
 static const char nptl_version[] __attribute_used__ = VERSION;
 
 
-#ifndef SHARED
-extern void __libc_setup_tls (size_t tcbsize, size_t tcbalign);
-#endif
-
 #ifdef SHARED
 static
 #else
@@ -288,18 +284,6 @@ static bool __nptl_initial_report_events __attribute_used__;
 void
 __pthread_initialize_minimal_internal (void)
 {
-#ifndef SHARED
-  /* Unlike in the dynamically linked case the dynamic linker has not
-     taken care of initializing the TLS data structures.  */
-  __libc_setup_tls (TLS_TCB_SIZE, TLS_TCB_ALIGN);
-
-  /* We must prevent gcc from being clever and move any of the
-     following code ahead of the __libc_setup_tls call.  This function
-     will initialize the thread register which is subsequently
-     used.  */
-  __asm __volatile ("");
-#endif
-
   /* Minimal initialization of the thread descriptor.  */
   struct pthread *pd = THREAD_SELF;
   __pthread_initialize_pids (pd);