When elftoolchain's objcopy (or strip) is rewriting a file in-place,

When elftoolchain's objcopy (or strip) is rewriting a file in-place,
make it create the temporary file in the same directory as the source
file by default, instead of always using $TMPDIR or /tmp. If creating
that file fails because the directory is not writable, also fallback to
$TMPDIR or /tmp.

This has also been submitted upstream as:
https://sourceforge.net/p/elftoolchain/tickets/597/

Reported by:	cem
PR:		250872
MFC after:	2 weeks