fixes issue 699 - redirect_realloc seg fault on mem is NULL
fixes issue 699
- redirect_realloc seg fault on mem is NULL

git-svn-id: ed337ca7cdb08c0ba29d8fe58632bb7686892c2d@1290 49cc7528-f6fd-11dd-9d1a-b59b2e1864b6

rnk/dynamorio,rnk/dynamorio,rnk/dynamorio,rnk/dynamorio,rnk/dynamorio