util: Add support for detection of gzipped packet traces
util: Add support for detection of gzipped packet traces

This patch adds support for automatically detecting a gzipped packet
trace, thus accepting either a compressed or uncompressed trace.

haowu4682/gem5,haowu4682/gem5,haowu4682/gem5,haowu4682/gem5,haowu4682/gem5,haowu4682/gem5,haowu4682/gem5,haowu4682/gem5,haowu4682/gem5