e2fsdroid: Refactor basefs allocation.

This refactors base_fs_alloc_load() to address two issues. First, the
failure cases have been made simpler by factoring out a common helper
for freeing a base_fs_allocator. Second, we no longer return
EXIT_FAILURE, since this is not an errcode_t.

Bug: 145316683
Change-Id: I8b28c684ecf3423b605b550177d7ead4eb2821a4
1 file changed