[BZ #16046] Static dlopen correction fallout fixes.

Fixes to address issues from BZ #15022 resolution, as follows:

* TLS updates to csu/libc-tls.c -- we now have a proper main map, so
  there's no longer a need to create a separate fake one to keep TLS
  structures,

* random updates to elf/dl-close.c -- LM_ID_BASE is now a valid name
  space ID for static executables as well, so assert that we don't
  unload the main map.  Similarly dl_nns isn't supposed to be 0 for
  static executables anymore,

* actual BZ #16046 fix to elf/dl-iteratephdr.c -- the dl_iterate_phdr
  special function for static executables isn't needed anymore, provided
  that l_phdr and l_phnum members of the main map have been properly
  initialized (done in _dl_non_dynamic_init in elf/dl-support.c now),

* ld.so.cache loader update to elf/dl-load.c --
  GL(dl_ns)[LM_ID_BASE]._ns_loaded is now always initialized in static
  executables so can become the fallback loader map to check for
  DF_1_NODEFLIB, provided that the l_flags_1 member of the main map has
  been properly initialized (done in elf/dl-support.c now); this also
  ensures previous semantics elsewhere in elf/dl-load.c,

* matching updates to elf/dl-support.c -- to complement the two fixes
  above.

1 files changed, 4 insertions, 10 deletions

diff --git a/elf/dl-load.c b/elf/dl-load.c
index ee12f329d8..1be7a3ca96 100644
--- a/elf/dl-load.c
+++ b/elf/dl-load.c
@@ -2233,23 +2233,17 @@ _dl_map_object (struct link_map *loader, const char *name,
 
 	  if (cached != NULL)
 	    {
-# ifdef SHARED
 	      // XXX Correct to unconditionally default to namespace 0?
 	      l = (loader
 		   ?: GL(dl_ns)[LM_ID_BASE]._ns_loaded
-		   ?: &GL(dl_rtld_map));
-# else
-	      l = loader;
+# ifdef SHARED
+		   ?: &GL(dl_rtld_map)
 # endif
+		  );
 
 	      /* If the loader has the DF_1_NODEFLIB flag set we must not
 		 use a cache entry from any of these directories.  */
-	      if (
-# ifndef SHARED
-		  /* 'l' is always != NULL for dynamically linked objects.  */
-		  l != NULL &&
-# endif
-		  __builtin_expect (l->l_flags_1 & DF_1_NODEFLIB, 0))
+	      if (__builtin_expect (l->l_flags_1 & DF_1_NODEFLIB, 0))
 		{
 		  const char *dirp = system_dirs;
 		  unsigned int cnt = 0;