update to the latest rust-vmm-ci and container

This crate was using a pretty old version of Rust (1.35.0) which
didn't have the required features.

Signed-off-by: Andreea Florescu <fandree@amazon.com>

.buildkite/pipeline.linux.yml

@@ -9,7 +9,7 @@ steps:
       os: linux
     plugins:
       - docker#v3.0.1:
-          image: "rustvmm/dev:v3"
+          image: "rustvmm/dev:v5"
           always-pull: true
 
   - label: "build-musl-x86-mmap"
@@ -22,7 +22,7 @@ steps:
       os: linux
     plugins:
       - docker#v3.0.1:
-          image: "rustvmm/dev:v3"
+          image: "rustvmm/dev:v5"
           always-pull: true
 
   - label: "build-gnu-arm-mmap"
@@ -35,7 +35,7 @@ steps:
       os: linux
     plugins:
       - docker#v3.0.1:
-          image: "rustvmm/dev:v3"
+          image: "rustvmm/dev:v5"
           always-pull: true
 
   - label: "build-musl-arm-mmap"
@@ -48,5 +48,5 @@ steps:
       os: linux
     plugins:
       - docker#v3.0.1:
-          image: "rustvmm/dev:v3"
+          image: "rustvmm/dev:v5"
           always-pull: true

coverage_config.json → coverage_config_aarch64.json

@@ -1,5 +1,5 @@
 {
-  "coverage_score": 84.9,
+  "coverage_score": 85.3,
   "exclude_path": "mmap_windows.rs",
   "crate_features": "backend-mmap,backend-atomic"
 }

coverage_config_x86_64.json

@@ -0,0 +1,5 @@
+{
+  "coverage_score": 85.3,
+  "exclude_path": "mmap_windows.rs",
+  "crate_features": "backend-mmap,backend-atomic"
+}