getdeps: enable -fcoroutines for GCC in fb303 and eden

Summary:
X-link: facebookincubator/zstrong#1019

Enable coroutines on GCC for fb303 and eden OSS cmake builds to match folly and [fbthrift](https://github.com/facebook/fbthrift/blob/197890bbedd4942809b91139f9a2890c8f167045/CMakeLists.txt#L64-L75).  This stops the eden tests from immediatedly core dumping when they try to open up the thrift server

So can check if core dumps:
   * fix to eden main.py to stub par_telemetry in OSS where its not available
   * add the missing getdeps dependency from eden to sapling for tests (it needs the sapling binaries for the tests torun)

Reviewed By: jdelliot

Differential Revision: D64911998

fbshipit-source-id: f6316908314bd821dd8c0e5afb5fe4584f5be23e

CMakeLists.txt

@@ -29,10 +29,19 @@ option(PYTHON_EXTENSIONS
   ON
 )
 
-set(CMAKE_CXX_STANDARD 17)
-set(CMAKE_CXX_STANDARD_REQUIRED ON)
+if(NOT CMAKE_CXX_STANDARD)
+  set(CMAKE_CXX_STANDARD 17)
+  set(CMAKE_CXX_STANDARD_REQUIRED ON)
+  message(STATUS "setting C++ standard to C++${CMAKE_CXX_STANDARD}")
+endif()
 set(CMAKE_CXX_EXTENSIONS OFF)
 
+# Explicitly enable coroutine support, since GCC does not enable it
+# by default when targeting C++17.
+if (CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
+  add_compile_options($<$<COMPILE_LANGUAGE:CXX>:-fcoroutines>)
+endif()
+
 set(INCLUDE_INSTALL_DIR include CACHE STRING
     "The subdirectory where header files should be installed")
 set(LIB_INSTALL_DIR lib CACHE STRING

build/fbcode_builder/manifests/eden

@@ -55,6 +55,10 @@ python
 # TODO: teach getdeps to compile lmdb on Windows.
 lmdb
 
+[dependencies.test=on]
+# sapling CLI is needed to run the tests
+sapling
+
 [shipit.pathmap.fb=on]
 # for internal builds that use getdeps
 fbcode/fb303 = fb303