[buck/java2] eliminate project root config flag

Summary:
Passing an absolute project path as buck config flag makes buck caching almost impossible for infer artefacts, since on every host/run that directory can be different.

Eliminate that and rely on shell commands to find the project root, executed within the genrule.

Reviewed By: jvillard

Differential Revision: D15963807

fbshipit-source-id: b6e590029

infer/src/integration/Buck.ml

@@ -160,9 +160,7 @@ let die_if_empty f = function [] -> f L.(die UserError) | l -> l
 let buck_config =
   lazy
     ( if Config.genrule_master_mode then
-      [ "infer.project_root=" ^ Utils.realpath Config.project_root
-      ; "infer.infer_out=" ^ Utils.realpath Config.results_dir
-      ; "infer.version=" ^ Version.versionString
+      [ "infer.version=" ^ Version.versionString
       ; "infer.infer_bin=" ^ Config.bin_dir ^/ Config.exe_basename
       ; "infer.mode=capture" ]
       |> List.fold ~init:[] ~f:(fun acc f -> "--config" :: f :: acc)

infer/tests/build_systems/genrulecapture/DEFS

@@ -7,12 +7,7 @@ def _get_infer_bin():
   return read_config("infer", "infer_bin")
 
 def _get_project_root():
-  return read_config("infer", "project_root")
-
-def _get_infer_deps():
-  infer_out = read_config("infer", "infer_out")
-  infer_deps = "{}/infer-deps.txt".format(infer_out)
-  return infer_deps
+  return "\$(git rev-parse --show-toplevel)/infer/tests/build_systems/genrulecapture"
 
 def _infer_capture_genrule(
     name,