libc/uClibc: move content of do_libc_headers into do_libc_start_files

It is unnecessary to split C library preparation into two steps, as only
one really makes sense. So, do_libc_headers is bound to be withdrawn
short-term, in favor of do_libc_start_files.

uClibc already had all its start files installation in do_libc_headers, and
do_libc_start_files was empty, just migrate the content of the former into
the latter.

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@anciens.enib.fr>

 diff -durN binutils-2.20.1.orig/ld/ldmain.c binutils-2.20.1/ld/ldmain.c

 --- binutils-2.20.1.orig/ld/ldmain.c	2010-08-17 19:32:17.000000000 +0200

 +++ binutils-2.20.1/ld/ldmain.c	2010-08-17 19:32:18.000000000 +0200

 @@ -264,6 +264,7 @@

    link_info.keep_memory = TRUE;

    link_info.new_dtags = TRUE;

    link_info.combreloc = TRUE;

 +  link_info.relro = TRUE;

    link_info.strip_discarded = TRUE;

    link_info.emit_hash = TRUE;

  #ifndef __mips__