Code refactor for the compression procedure which includes:
1. Move qemu_compress_data and qemu_put_compression_data from qemu-file.c to
ram.c, for the reason that most part of the code logical has nothing to do
with qemu-file. Besides, the decompression code is located at ram.c only.
2. Simplify
Code refactor for the compression procedure which includes:
1. Move qemu_compress_data and qemu_put_compression_data from qemu-file.c to
ram.c, for the reason that most part of the code logical has nothing to do
with qemu-file. Besides, the decompression code is located at ram.c only.
2. Simplify
