build: remove jemalloc flag --enable-cc-silence
build: remove jemalloc flag --enable-cc-silence

This change removes the message: `configure: WARNING: unrecognized
options: --enable-cc-silence` when build fluent-bit.

The flag was replace by --disable-cc-silence in jemalloc v4.0.0
https://github.com/jemalloc/jemalloc/commit/644d414bc9ab52efbbf7ebeb350170106ec1f937

Signed-off-by: Haitao Li <1546787094a174f65e7b6f11359a040df0a1bd97@gmail.com>

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