Build with C++17

This will require a reasonably modern toolchain. I've put minimum compiler
versions in the README based on versions in
https://en.cppreference.com/w/cpp/compiler_support that have mostly complete
language and library support.

The minimum Bazel version bump is unrelated, but 0.28 is definitely not
supported anymore.

Please report issues on gvisor.dev/issue/1349.

Fixes #1349

PiperOrigin-RevId: 284274250

.bazelrc

@@ -12,6 +12,9 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+# Build with C++17.
+build --cxxopt=-std=c++17
+
 # Display the current git revision in the info block.
 build --stamp --workspace_status_command tools/workspace_status.sh
 

README.md

@@ -48,9 +48,10 @@ Make sure the following dependencies are installed:
 
 *   Linux 4.14.77+ ([older linux][old-linux])
 *   [git][git]
-*   [Bazel][bazel] 0.28.0+
+*   [Bazel][bazel] 1.2+
 *   [Python][python]
 *   [Docker version 17.09.0 or greater][docker]
+*   C++ toolchain supporting C++17 (GCC 7+, Clang 5+)
 *   Gold linker (e.g. `binutils-gold` package on Ubuntu)
 
 ### Building