add re2 as cmake dependency

Summary:
We use Re2 in D22877942 for parsing multiple path prefix data fetch logging,
this introduces the dependency for eden's opensource builds.

Reviewed By: chadaustin

Differential Revision: D23431175

fbshipit-source-id: 44b399e92cb89ba1403295ecd10bc8f8d769b02c

build/fbcode_builder/CMake/FindRe2.cmake

+# Copyright (c) Facebook, Inc. and its affiliates.
+#
+# This software may be used and distributed according to the terms of the
+# GNU General Public License version 2.
+
+find_library(RE2_LIBRARY re2)
+mark_as_advanced(RE2_LIBRARY)
+
+find_path(RE2_INCLUDE_DIR NAMES re2/re2.h)
+mark_as_advanced(RE2_INCLUDE_DIR)
+
+include(FindPackageHandleStandardArgs)
+FIND_PACKAGE_HANDLE_STANDARD_ARGS(
+     RE2
+     REQUIRED_VARS RE2_LIBRARY RE2_INCLUDE_DIR)
+
+if(RE2_FOUND)
+  set(RE2_LIBRARY ${RE2_LIBRARY})
+  set(RE2_INCLUDE_DIR, ${RE2_INCLUDE_DIR})
+endif()

build/fbcode_builder/manifests/eden

@@ -17,6 +17,7 @@ fbthrift
 fb303
 cpptoml
 rocksdb
+re2
 libgit2
 lz4
 pexpect