util/disk_cache: fix compressed size calculation
util/disk_cache: fix compressed size calculation

It incorrectly doubles the size on each iteration.

Fixes: 85a9b1b5 "util/disk_cache: compress individual cache entries"

Signed-off-by: Grazvydas Ignotas <eac34e836c3bc120048c86fead6dd0257a872a9e@gmail.com>
Reviewed-by: Timothy Arceri <c48760dafc316d20cf5b0817150c999e82cd892f@itsqueeze.com>

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler