hot restarter: Log errno for 'panic: cannot open shared memory' error (#4032)
hot restarter: Log errno for 'panic: cannot open shared memory' error (#4032)

The error message right now assumes that the errno is EACCESS which
isn't necessarily true. Logging the errno makes this easier to debug.

Signed-off-by: Julia Evans <b43b0ad1e8108e7ab870d7a54feac93ae8b8600e@stripe.com>

eklitzke/envoy,lyft/envoy,istio/envoy,istio/envoy,envoyproxy/envoy,jrajahalme/envoy,lizan/envoy,eklitzke/envoy,envoyproxy/envoy-wasm,istio/envoy,envoyproxy/envoy,istio/envoy,envoyproxy/envoy-wasm,lyft/envoy,envoyproxy/envoy,istio/envoy,lizan/envoy,envoyproxy/envoy-wasm,lyft/envoy,dnoe/envoy,envoyproxy/envoy,lyft/envoy,lizan/envoy,envoyproxy/envoy,eklitzke/envoy,lizan/envoy,envoyproxy/envoy-wasm,envoyproxy/envoy-wasm,envoyproxy/envoy-wasm,istio/envoy,lyft/envoy,envoyproxy/envoy,jrajahalme/envoy,envoyproxy/envoy,istio/envoy,jrajahalme/envoy,eklitzke/envoy,envoyproxy/envoy,envoyproxy/envoy-wasm,eklitzke/envoy,eklitzke/envoy,lizan/envoy,dnoe/envoy,dnoe/envoy,jrajahalme/envoy,dnoe/envoy,envoyproxy/envoy,lyft/envoy,envoyproxy/envoy,envoyproxy/envoy,jrajahalme/envoy,jrajahalme/envoy,lizan/envoy,dnoe/envoy,envoyproxy/envoy