bug#21613: Include messes up when compiling file in load path

[Taylan Ulrich Bayırlı/Kammer]

When a file to be compiled, A.scm, contains (include "B.scm"), the
compiler fails to find B.scm if the directory containing A and B are in
Guile's load path.

Here's a shell transcript showcasing the bug:

--- snip ---
$ mkdir test
$ echo '(include "test2.scm")' > test/test1.scm
$ echo '(display "foo\n")' > test/test2.scm
$ pwd
/home/taylan
$ export GUILE_LOAD_PATH=/home/taylan/test
$ unset GUILE_LOAD_COMPILED_PATH
$ guile -q
GNU Guile 2.0.11
Copyright (C) 1995-2014 Free Software Foundation, Inc.

Guile comes with ABSOLUTELY NO WARRANTY; for details type `,show w'.
This program is free software, and you are welcome to redistribute it
under certain conditions; type `,show c' for details.

Enter `,help' for help.
scheme@(guile-user)> (compile-file "/home/taylan/test/test1.scm")
ice-9/boot-9.scm:106:20: In procedure #<procedure 248a580 at 
ice-9/boot-9.scm:97:6 (thrown-k . args)>:
ice-9/boot-9.scm:106:20: In procedure open-file: No such file or directory: 
"./test2.scm"

Entering a new prompt.  Type `,bt' for a backtrace or `,q' to continue.
scheme@(#{ g269}#) [1]>
--- snip ---

This seems to be related to 'compile-file' setting
'%file-port-name-canonicalization' to 'relative', but I don't know what
the correct fix is.

Taylan