thrift: yarpl/rsocket should be not required deps

Summary:
This didn't show up in our internal CI during development,
because the affected projects do their own fetches from the git repos.

Reviewed By: simpkins

Differential Revision: D13819124

fbshipit-source-id: 741742d88ac6095253c318c197b165e53f67740e

CMakeLists.txt

@@ -89,8 +89,8 @@ if(lib_only OR build_all)
   find_package(GFlags REQUIRED)
   find_package(Glog REQUIRED)
   find_package(folly CONFIG REQUIRED)
-  find_package(yarpl CONFIG REQUIRED)
-  find_package(rsocket CONFIG REQUIRED)
+  find_package(yarpl CONFIG)
+  find_package(rsocket CONFIG)
   find_package(fizz CONFIG REQUIRED)
   find_package(wangle CONFIG REQUIRED)
   find_package(Zlib REQUIRED)

thrift/lib/cpp2/CMakeLists.txt

@@ -58,6 +58,13 @@ target_link_libraries(
 
 bypass_source_check("${RpcMetadata-cpp2-SOURCES}")
 bypass_source_check("${rsocket-cpp2-SOURCES}")
+
+if(TARGET rsocket::ReactiveSocket)
+  list(APPEND rsocket-cpp2-SOURCES
+    async/RSocketClientChannel.cpp
+  )
+endif()
+
 add_library(
   thriftcpp2
 
@@ -75,7 +82,6 @@ add_library(
   async/PcapLoggingHandler.cpp
   async/RequestChannel.cpp
   async/ResponseChannel.cpp
-  async/RSocketClientChannel.cpp
   gen/field_ref.cpp
   server/BaseThriftServer.cpp
   server/Cpp2Connection.cpp