dtrace: migrate stacktrace dumping and move headers about: fix reloc overrun

dtrace: migrate stacktrace dumping and move headers about: fix reloc overrun

Stacktrace dumping has been moved to the GPL-licensed dtrace_os.c because it
depends on a symbol that is exported as GPL-only.  Functionality in dtrace_isa
that requires stacktrace dumping can now use dtrace_stacktrace().

The GPL-licensed dtrace_os.h C header file is now made available through the
/include/linux hierarchy, and it is included in dtrace.h.

Fixed a bug in dtrace_relocs.c where section names where copied into a memory
area that was 1 byte short, causing various unpleasant forms of behaviour.

Signed-off-by: Kris Van Hees <kris.van.hees@oracle.com>