JFFS2 rtime decompression bug

Summary

The rtime decompressor appears to have a bug when handling corrupted/bad compressed data. The repeat while loop doesn't verify it has space to write out data when handling repeats.

This was observed to cause memory corruption when using multiple JFFS2 partitions set to use the same compression buffer (which is itself a bug/incorrect configuration).

Steps to reproduce

Configure a system with multiple JFFS2 filesystems configured to use the same rtime compression buffer and access them from multiple threads. RAM and flash corruption occur quickly.