Added Bazel Workspace with initial targets

Added minimal bazel workspace with initialized `rules_rust` with the
nightly compiler set to the date mentioned in `rust-toolchain` file in
root of the repository.

Expanded `.gitignore` with bazel artifacts folders and `bazel`
plugin temp folder.

`sgx_types`, `sgx_libc` and `sgx_trts` have been ported to `rust_library`
bazel targets, with default cargo features set on.

Signed-off-by: Urban Avsec <[email protected]>

.bazelversion

@@ -0,0 +1 @@
+0.28.1

.gitignore

@@ -25,3 +25,11 @@ samplecode/**/target
 
 #generated assembly
 third_party/ring/pregenerated
+
+#Bazel
+.clwb
+bazel-bin
+bazel-genfiles
+bazel-out
+bazel-rust-sgx-sdk
+bazel-testlogs

WORKSPACE

@@ -0,0 +1,37 @@
+load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
+load("@bazel_tools//tools/build_defs/repo:git.bzl", "git_repository")
+
+##############################################
+#                                            #
+#                   Rust                     #
+#                                            #
+##############################################
+http_archive(
+    name = "io_bazel_rules_rust",
+    sha256 = "29d9fc1cdbd737c51db5983d1ac8e64cdc684c4683bafbcc624d3d81de92a32f",
+    strip_prefix = "rules_rust-8417c8954efbd0cefc8dd84517b2afff5e907d5a",
+    urls = [
+        "https://github.com/bazelbuild/rules_rust/archive/8417c8954efbd0cefc8dd84517b2afff5e907d5a.tar.gz",
+    ],
+)
+
+http_archive(
+    name = "bazel_skylib",
+    sha256 = "eb5c57e4c12e68c0c20bc774bfbc60a568e800d025557bc4ea022c6479acc867",
+    strip_prefix = "bazel-skylib-0.6.0",
+    url = "https://github.com/bazelbuild/bazel-skylib/archive/0.6.0.tar.gz",
+)
+
+load("@io_bazel_rules_rust//rust:repositories.bzl", "rust_repository_set")
+
+rust_repository_set(
+    name = "rust_linux_x86_64",
+    exec_triple = "x86_64-unknown-linux-gnu",
+    extra_target_triples = [],
+    iso_date = "2019-05-22",
+    version = "nightly",
+)
+
+load("@io_bazel_rules_rust//:workspace.bzl", "bazel_version")
+
+bazel_version(name = "bazel_version")

sgx_libc/BUILD

@@ -0,0 +1,10 @@
+load("@io_bazel_rules_rust//rust:rust.bzl", "rust_library")
+
+rust_library(
+    name = "sgx_libc",
+    srcs = glob(["src/*.rs"]),
+    crate_features = ["align"],
+    edition = "2018",
+    visibility = ["//visibility:public"],
+    deps = ["//sgx_types"],
+)

sgx_trts/BUILD

@@ -0,0 +1,12 @@
+load("@io_bazel_rules_rust//rust:rust.bzl", "rust_library")
+
+rust_library(
+    name = "sgx_trts",
+    srcs = glob(["src/*.rs"]),
+    edition = "2018",
+    visibility = ["//visibility:public"],
+    deps = [
+        "//sgx_libc",
+        "//sgx_types",
+    ],
+)

sgx_types/BUILD

@@ -0,0 +1,9 @@
+load("@io_bazel_rules_rust//rust:rust.bzl", "rust_library")
+
+rust_library(
+    name = "sgx_types",
+    visibility = ["//visibility:public"],
+    edition = "2018",
+    srcs = glob(["src/*.rs"]),
+    deps = [],
+)