add file hint to add-patches-section

Currently, add-patches-section just blindly looks in vmlinux
for a function symbol matching the name of the patched function
in the input object file.  However, for local symbols, they may
appear multiple times in the vmlinux symbol table since the symbol
name may be reused locally in different files.

This commit add support for "file hinting".  It tracks what
file the symbol is in and searches for local symbols within
that file in vmlinux first.  If it doesn't find one, it then
searches globally like it always has.

Fixes issue #53

Signed-off-by: Seth Jennings <sjenning@redhat.com>
remove dead code

Signed-off-by: Seth Jennings <sjenning@redhat.com>
remove obsolete comment

Signed-off-by: Seth Jennings <sjenning@redhat.com>
add file hint to link-vmlinux-syms

Same as "add file hint to add-patches-section" to fix
symbol name collisions when looking up in vmlinux

Fixes issue #54

Signed-off-by: Seth Jennings <sjenning@redhat.com>
remove obsolete comment

Signed-off-by: Seth Jennings <sjenning@redhat.com>
add TODO to de-dup code

Signed-off-by: Seth Jennings <sjenning@redhat.com>