The problem happens when trying to use a shared archive. If for some
reason mapping the shared file fails,
to undo the earlier call to
Unfortunately the resize code is not prepared to deal with a zero-sized
region so an assert fails.
Rather than touch the resize code, this fix changes the caller to only
once after the shared file is mapped.
Tested fix on a particular linux arm platform where the mmap fails 100%
of the time due to a different issue.
Ran -Xshare:dump first then a few GC tests.