[PATCH] Fix core files so they make sense to gdb...

It is silly to use non-static variable for writting zeroes to the file.

And more seriously, foffset in core dump file dump function was incremented
too much, so some parts of core dump were shifted by size of few phdrs and
notes down, so although gdb was able to load that file, it did not make lot
of sense - in my test case data pages were shifted down by about 900 bytes.

Signed-off-by: Petr Vandrovec <petr@vandrovec.name>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>