Support build on non Linux platforms

cargo config
1. MUSL is no longer the default target. This allows building on Mac and Windows.
2. On Linux, code coverage compiler options are supplied by default.

pre-commit, pre-push
- Coverage is turned on only on Linux
- clippy is run on all platforms

github
- MUSL build is tested to ensure that stand alone executables can be created

Signed-off-by: Anand Krishnamoorthi <anakrish@microsoft.com>

.github/workflows/rust.yml

@@ -28,3 +28,7 @@ jobs:
       run: cargo clippy --all-targets --no-deps -- -Dwarnings
     - name: Run tests
       run: cargo test --verbose
+    - name: Build (MUSL)
+      run: cargo build --verbose --all-targets --target x86_64-unknown-linux-musl
+    - name: Run tests (MUSL)
+      run: cargo test --verbose --target x86_64-unknown-linux-musl