elf: Avoid nested functions in the loader [BZ #27220]

dynamic-link.h is included more than once in some elf/ files (rtld.c,
dl-conflict.c, dl-reloc.c, dl-reloc-static-pie.c) and uses GCC nested
functions. This harms readability and the nested functions usage
is the biggest obstacle prevents Clang build (Clang doesn't support GCC
nested functions).

The key idea for unnesting is to add extra parameters (struct link_map
*and struct r_scope_elm *[]) to RESOLVE_MAP,
ELF_MACHINE_BEFORE_RTLD_RELOC, ELF_DYNAMIC_RELOCATE, elf_machine_rel[a],
elf_machine_lazy_rel, and elf_machine_runtime_setup. (This is inspired
by Stan Shebs' ppc64/x86-64 implementation in the
google/grte/v5-2.27/master which uses mixed extra parameters and static
variables.)

Future simplification:
* If mips elf_machine_runtime_setup no longer needs RESOLVE_GOTSYM,
  elf_machine_runtime_setup can drop the `scope` parameter.
* If TLSDESC no longer need to be in elf_machine_lazy_rel,
  elf_machine_lazy_rel can drop the `scope` parameter.

Tested on aarch64, i386, x86-64, powerpc64le, powerpc64, powerpc32,
sparc64, sparcv9, s390x, s390, hppa, ia64, armhf, alpha, and mips64.
In addition, tested build-many-glibcs.py with {arc,csky,microblaze,nios2}-linux-gnu
and riscv64-linux-gnu-rv64imafdc-lp64d.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

elf/dl-reloc-static-pie.c

@@ -19,8 +19,14 @@
 #if ENABLE_STATIC_PIE
 /* Mark symbols hidden in static PIE for early self relocation to work.  */
 # pragma GCC visibility push(hidden)
+#include <assert.h>
 #include <unistd.h>
 #include <ldsodefs.h>
+
+#include <dl-machine.h>
+
+#define STATIC_PIE_BOOTSTRAP
+#define RESOLVE_MAP(map, scope, sym, version, flags) map
 #include "dynamic-link.h"
 
 /* Relocate static executable with PIE.  */
@@ -30,11 +36,6 @@ _dl_relocate_static_pie (void)
 {
   struct link_map *main_map = _dl_get_dl_main_map ();
 
-# define STATIC_PIE_BOOTSTRAP
-# define BOOTSTRAP_MAP (main_map)
-# define RESOLVE_MAP(sym, version, flags) BOOTSTRAP_MAP
-# include "dynamic-link.h"
-
   /* Figure out the run-time load address of static PIE.  */
   main_map->l_addr = elf_machine_load_address ();
 
@@ -53,12 +54,12 @@ _dl_relocate_static_pie (void)
   elf_get_dynamic_info (main_map);
 
 # ifdef ELF_MACHINE_BEFORE_RTLD_RELOC
-  ELF_MACHINE_BEFORE_RTLD_RELOC (main_map->l_info);
+  ELF_MACHINE_BEFORE_RTLD_RELOC (main_map, main_map->l_info);
 # endif
 
   /* Relocate ourselves so we can do normal function calls and
      data access using the global offset table.  */
-  ELF_DYNAMIC_RELOCATE (main_map, 0, 0, 0);
+  ELF_DYNAMIC_RELOCATE (main_map, NULL, 0, 0, 0);
   main_map->l_relocated = 1;
 
   /* Initialize _r_debug_extended.  */