Use unstripped binaries in fuzz target packaging.

Unstripped binaries allow for online symbolization, and offline
symbolization using the debug info in the binary. Debug information
isn't stripped for host binaries, but is for target. Target should also
contain debugging info.

Bug: N/A
Test: m fuzz && # Check that fuzz targets in the fuzz-*.zip package have
debug info.

Change-Id: Ibd3002674d519e927340a50dfdfbf44f2d809d58