add zlib as an explicit dependency for getdeps build

Summary:
needed for QUIC/H3 interop

also make it possible to run getdeps build with extra arguments (--no-tests for
example)

Reviewed By: mjoras

Differential Revision: D24925777

fbshipit-source-id: fbdc1aa56e398d295ef8dac0ad0bab03bd7bd803

Author: lnicco

build/fbcode_builder/manifests/proxygen

@@ -24,6 +24,7 @@ BUILD_TESTS = ON
 BUILD_TESTS = OFF
 
 [dependencies]
+zlib
 gperf
 folly
 fizz