[arm] Move some generated files out of the source tree

[arm] Move some generated files out of the source tree

When I originally started work on the new options framework for ARM
I'd worked on the assumption that AWK might not be available on every
build machine (only on developer's machines).  However, looking again
I notice that all the options framework relies on it being present for
every build.  This means that some of the generated files that come
from running parsecpu.awk do not need to be kept under revision
control.

Unfortunately, it's not _all_ generated files.  The build
infrastructure assumes that all .md fragments are in the source tree
and similarly that all .opt fragments are there as well.

Still, eliminating the very big .h files is a step forward as they are
very regular in structure and diff/patch/merge tools can sometimes
make mistakes when resolving conflicts.

So this patch removes the generated .h files from the source tree and
tweaks the make rules accordingly.  I've also changed the build rules
to use the stamp technique to eliminate some false dependencies in a
rebuild.

Top-level:

* contrib/gcc_update (files_and_dependencies): Remove stamp rules for
arm-specific auto-generated header files.

gcc:
* common/config/arm/arm-common.c: Adjust include path for
arm-cpu-cdata.h
* t-arm (TM_H): Adjust path for arm-cpu.h.
(arm-cpu.h): Create in build directory.  Adjust dependency rules.
(arm-cpu-data.h): Likewise.
(arm-cpu-cdata.h): Likewise.
* config/arm/arm-cpu.h: Delete.
* config/arm/arm-cpu-cdata.h: Delete.
* config/arm/arm-cpu-data.h: Delete.

From-SVN: r249971