Increase MSRV coverage for supported platforms in CI

Let's be nice and check the MSRV (at least once) for each supported
platform according to `README.md`. We differentiate Linux further with
respect to udev/musl, so it gets a special treatment.

Our examples currently do not build with MSRV. Let's work around this by
not building them for the new MSRV check msrv-x86_64-unknown-linux-musl
for now.

.github/workflows/ci.yaml

@@ -48,8 +48,34 @@ jobs:
 
   # --------------------------------------------------------------------------
   # MSRV
+  #
+  # Check at least once per platform.
 
-  msrv:
+  msrv-aarch64-apple-darwin:
+    uses: ./.github/workflows/build.yaml
+    with:
+      disable_extra_builds: true
+      disable_tests: true
+      target: aarch64-apple-darwin
+      toolchain: "1.59.0"
+
+  msrv-arm-linux-androideabi:
+    uses: ./.github/workflows/build.yaml
+    with:
+      disable_extra_builds: true
+      disable_tests: true
+      target: arm-linux-androideabi
+      toolchain: "1.59.0"
+
+  msrv-x86_64-unknown-freebsd:
+    uses: ./.github/workflows/build.yaml
+    with:
+      disable_extra_builds: true
+      disable_tests: true
+      target: x86_64-unknown-freebsd
+      toolchain: "1.59.0"
+
+  msrv-x86_64-unknown-linux-gnu:
     uses: ./.github/workflows/build.yaml
     with:
       disable_extra_builds: true
@@ -58,6 +84,31 @@ jobs:
       target: x86_64-unknown-linux-gnu
       toolchain: "1.59.0"
 
+  msrv-x86_64-unknown-linux-musl:
+    uses: ./.github/workflows/build.yaml
+    with:
+      disable_tests: true
+      extra_packages: gcc-aarch64-linux-gnu
+      target: aarch64-unknown-linux-musl
+      toolchain: "1.59.0"
+
+  msrv-x86_64-pc-windows-msvc:
+    uses: ./.github/workflows/build.yaml
+    with:
+      disable_extra_builds: true
+      disable_tests: true
+      runs_on: windows-2019
+      target: x86_64-pc-windows-msvc
+      toolchain: "1.59.0"
+
+  msrv-x86_64-unknown-netbsd:
+    uses: ./.github/workflows/build.yaml
+    with:
+      disable_extra_builds: true
+      disable_tests: true
+      target: x86_64-unknown-netbsd
+      toolchain: "1.59.0"
+
   # --------------------------------------------------------------------------
   # cargo-deny
 
@@ -106,6 +157,7 @@ jobs:
   aarch64-unknown-linux-musl:
     uses: ./.github/workflows/build.yaml
     with:
+      disable_extra_builds: true
       disable_tests: true
       extra_packages: gcc-aarch64-linux-gnu
       target: aarch64-unknown-linux-musl