bug#24721: 25.1; Reverse the order of `isearch-message-prefix' prefixes from function advice property

[Drew Adams]

When there is multiple advice (from `add-function') of
`isearch-filter-predicate' that has property `isearch-message-prefix',
these prefixes are currently shown left to right in the Isearch prompt,
with the first added being on the left and the last added being on the
right.

I think this is backwards from what a user expects.  I've reversed the
order in my own copy, and I think it is more helpful: The first one you
see is the latest applied.  Entries are added and removed on the left,
not the right.  The most important such prefix is typically the last
one applied, and having it on the left makes it more noticeable (IMO).

If you agree, all that's required is changing, in the
`isearch-message-prefix' code, (concat np prefix) to (concat prefix np).


In GNU Emacs 25.1.1 (x86_64-w64-mingw32)
 of 2016-09-17
Windowing system distributor `Microsoft Corp.', version 6.1.7601
Configured using:
 `configure --without-dbus --without-compress-install CFLAGS=-static'