Revert the last change

It has been fixed by

commit 4199e3b8669d0a36448687850374fdc2ad7240b6
Author: Alan Modra <amodra@gmail.com>
Date:   Wed Jan 15 21:50:55 2014 +1030

    non-PIC references to __ehdr_start in pie and shared

    Rather than hacking every backend to not discard dynamic relocations
    against an undefined hidden __ehdr_start, make it appear to be defined
    early.  We want __ehdr_start hidden before size_dynamic_sections so
    that it isn't put in .dynsym, but we do need the dynamic relocations
    for a PIE or shared library with a non-PIC reference.  Defining it
    early is wrong if we don't actually define the symbol later to its
    proper value.  (In some cases we want to leave the symbol undefined,
    for example, when the ELF header isn't loaded, and we don't have this
    infomation available in before_allocation.)

	* elf32-i386.c (elf_i386_allocate_dynrelocs): Revert the last
	change.
	* elf64-x86-64.c (elf_x86_64_allocate_dynrelocs): Likewise.
Small fixes to the GDB/MI Output Syntax grammar.

This patch fixes the grammar, and tries to do it in a way that makes
the logic behind the current implementation a little clearer.

gdb/doc/ChangeLog:

        (from Yuanhui Zhang  <asmwarrior@gmail.com>)
        (from Joel Brobecker  <brobecker@adacore.com>)
        * gdb.texinfo (GDB/MI Output Syntax): Add some missing "nl"
        markers.  Remove one that was misplaced.
Add missing empty line after declarations in "if" block (py-type.c).

This patch fixes a small coding-style violation...

gdb/ChangeLog:

        * python/py-type.c (convert_field): Add missing empty line
        after declarations.
Fix small style violation in py-value.c:get_field_type

gdb/ChangeLog:

        * python/py-value.c (get_field_type): Remove unnecessary curly
        braces for single-statement if block.

Tested on x86_64-linux.
introduce async_callback_ftype

This introduces async_callback_ftype.  This is needed for
make-target-delegates to work properly, as it doesn't implement a real
parser.  I think it's also an ok cleanup in its own right.

2014-01-15  Tom Tromey  <tromey@redhat.com>

	* target.h (async_callback_ftype): New typedef.
	(struct target_ops) <to_async>: Use it.
Silence uninitialized warning on ehdr_start_save

Older GCC, like 4.1/4.2, will issue an uninitialized warning on
ehdr_start_save.  This patch silences by using

struct bfd_link_hash_entry ehdr_start_save = ehdr_start_save;

	* emultempl/elf32.em (gld${EMULATION_NAME}_before_allocation):
	Silence uninitialized warning on ehdr_start_save with older
	GCC.