[Bug ada/57795] Fail Canadian cross building Ada

["yselkowitz at users dot sourceforge.net" <gcc-bugzilla@gcc.gnu.org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57795

Yaakov (Cygwin Ports) <yselkowitz at users dot sourceforge.net> changed:

           What    |Removed                     |Added
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                 CC|                            |yselkowitz at users dot sourceforg
                   |                            |e.net

--- Comment #1 from Yaakov (Cygwin Ports) <yselkowitz at users dot sourceforge.net> ---
I also ran into this when cross-compiling a native gcc with Ada
(i686-pc-cygwin/x86_64-pc-cygwin/x86_64-pc-cygwin) in the process of porting
GNAT to a new platform.  In fact, I believe this would happen any time $build
!= $host (regardless of $target), but NOT with the typical cross-compiler
($build == $host, $host != $target).

The root of the problem is RTS_DIR override (immediately prior to
gnattools-cross rule) in gnattools/Makefile.in, which calls gnatls (for $build)
where IIUC it should be something like $(GNATMAKE:gnatmake=gnatls) (for $host).

There is another problem in this situation: in
gcc/ada/gcc-interface/Make-lang.in, the xgnatugn rule (part of building
doc/projects.texi and doc/gnat_ugn.texi) calls $(GNATMAKE), resulting in a
xgnatugn which runs on $host instead of $build; this probably needs to be just
gnatmake instead.