Fix compilation problem of memcheck/tests/leak-segv-jmp on ppc32
With the change, the test compiles on ppc32.
However, the test fails miserably with
 Segmentation fault
while the whole purpose of the test was to see the leak search
would *not* segfault.

More investigations needed, but still committing as is to let
the tests compile and run.



git-svn-id: svn://svn.valgrind.org/valgrind/trunk@13612 a5019735-40e9-0310-863c-91ae7b9d1cf9