[gold patch] Add warning for executable stacks

[Cary Coutant <ccoutant at google dot com>]

This patch adds a --warn-execstack option, to have the linker print a
warning for any object that will cause the output to have an
executable stack.

I tested by hand with the existing memory_test test case, but I'm not
sure if it's reasonable to bake into a test case the assumption that
the assembler by default will leave out the .note.GNU-stack section,
or that the --execstack and --noexecstack options to gas are portable.

OK?

-cary


        * layout.cc (Layout::layout_gnu_stack): Add warnings for executable
        stack.
        * layout.h (Layout::layout_gnu_stack): Add pointer to Object
        parameter; change all callers.
        * object.cc (Sized_relobj::do_layout): Adjust call to layout_gnu_stack.
        * options.h (warn_execstack): New option.

Attachment: gold-warn-execstack-patch.txt
Description: Text document