create-diff-object: .isra fix

When renaming a foo.isra.1 function, there might also be a foo_bar
function which would be falsely matched with the current strchr logic.
Instead of matching the "foo" prefix, match "foo.isra".
create-diff-object: add support for gcc-mangled .part
create-diff-object: bundling for .text.unlikely symbols

With -ffunction-sections, some section names are given a prefix of
".text.unlikely." rather than just ".text.".
Merge pull request #234 from jpoimboe/isra-fix

create-diff-object: more special section fixes