Fix calculation of synthetic symbol sizes (ppc64)

The attached patch fixes a problem where nm displays bogus information for
synthetic symbol sizes when --size-sort is used.

This happens because the synthetic symbols (dot symbols for ppc64) are
generated based on their non-dot symbols. The generation process doesn't copy
over the ELF-specific bits of the regular non-dot symbols.

When --size-sort is used, the code attempts to access the symbol size from
the ELF-specific bits and ends up reading gargabe, causing the size to be
displayed incorrectly.

With the patch, i can see dot and non-dot symbols having the same size with
--size-sort.

This doesn't fix the fact that we don't display size information for synthetic
symbols without --size-sort, which i may address in the future.

binutils/ChangeLog:

2016-12-01  Luis Machado  <lgustavo@codesourcery.com>

	* nm.c (sort_symbols_by_size): Don't read symbol size if symbol
	is synthetic.

binutils/ChangeLog

@@ -1,3 +1,8 @@
+2016-12-01  Luis Machado  <lgustavo@codesourcery.com>
+
+	* nm.c (sort_symbols_by_size): Don't read symbol size if symbol
+	is synthetic.
+
 2016-11-30  Nick Clifton  <nickc@redhat.com>
 
 	PR ld/20815

binutils/nm.c

@@ -762,6 +762,7 @@ sort_symbols_by_size (bfd *abfd, bfd_boolean is_dynamic, void *minisyms,
       asection *sec;
       bfd_vma sz;
       asymbol *temp;
+      int synthetic = (sym->flags & BSF_SYNTHETIC);
 
       if (from + size < fromend)
 	{
@@ -777,9 +778,11 @@ sort_symbols_by_size (bfd *abfd, bfd_boolean is_dynamic, void *minisyms,
 
       sec = bfd_get_section (sym);
 
-      if (bfd_get_flavour (abfd) == bfd_target_elf_flavour)
+      /* Synthetic symbols don't have a full type set of data available, thus
+	 we can't rely on that information for the symbol size.  */
+      if (!synthetic && bfd_get_flavour (abfd) == bfd_target_elf_flavour)
 	sz = ((elf_symbol_type *) sym)->internal_elf_sym.st_size;
-      else if (bfd_is_com_section (sec))
+      else if (!synthetic && bfd_is_com_section (sec))
 	sz = sym->value;
       else
 	{