[libunwind] Adjust libunwind_01.pass.cpp test for ARM EHABI

ARM EHABI unwinding tables only store the start address of each function, so the
last function is assumed to cover the entire address space after it. The test
picks an address on the stack assuming that it's in no function, but because of
the above it's actually resolved to the last function. Fix this by using address
0 instead.

Differential Revision: https://reviews.llvm.org/D68387

llvm-svn: 373628