Fix 2 bugs in memory mapping setup:
- the invalid region at offset 0 was not protected because mmap at
address 0 fails with EPERM on most Linux systems. We did not
notice this because the check condition was flipped: the code was
checking that mprotect has failed. And the test that was supposed
to catch this was weakened by the mitigations in the mmap
interceptor.
- when running without origins, the origin shadow range was left
unprotected.
The new test ensures that mmap w/o MAP_FIXED always returns valid
application addresses.
llvm-svn: 238109
45328240dc