Move FindZstd.cmake into fbcode_builder

Summary:
A bunch of existing projects vendor it into their own CMake folder. But these
same projects also have fbcode_builder's CMake directory in their CMAKE_MODULE_PATH,
so move FindZstd here.

Differential Revision: D29637686

fbshipit-source-id: 805676e18f98ef217dea8511d039edc38771b529

build/fbcode_builder/CMake/FindZstd.cmake

+# Copyright (c) Facebook, Inc. and its affiliates.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+#
+# - Try to find Facebook zstd library
+# This will define
+# ZSTD_FOUND
+# ZSTD_INCLUDE_DIR
+# ZSTD_LIBRARY
+#
+
+find_path(ZSTD_INCLUDE_DIR NAMES zstd.h)
+
+find_library(ZSTD_LIBRARY_DEBUG NAMES zstdd zstd_staticd)
+find_library(ZSTD_LIBRARY_RELEASE NAMES zstd zstd_static)
+
+include(SelectLibraryConfigurations)
+SELECT_LIBRARY_CONFIGURATIONS(ZSTD)
+
+include(FindPackageHandleStandardArgs)
+FIND_PACKAGE_HANDLE_STANDARD_ARGS(
+    ZSTD DEFAULT_MSG
+    ZSTD_LIBRARY ZSTD_INCLUDE_DIR
+)
+
+if (ZSTD_FOUND)
+    message(STATUS "Found Zstd: ${ZSTD_LIBRARY}")
+endif()
+
+mark_as_advanced(ZSTD_INCLUDE_DIR ZSTD_LIBRARY)