Add caching for cargo files in CI

Former-commit-id: 04839f9f3f387c7d14391e0a8440eda42ed960e2
Former-commit-id: 56de0ffa4bbca27c3a125bcb78d0195c42068f7f

.github/workflows/build.yml

@@ -21,6 +21,22 @@ jobs:
         sudo apt-get install libsdl2-dev
         sudo apt-get install libsdl2-image-dev
 
+    - name: Cache cargo registry
+      uses: actions/cache@v1
+      with:
+        path: ~/.cargo/registry
+        key: ${{ runner.os }}-cargo-registry-${{ hashFiles('**/Cargo.lock') }}
+    - name: Cache cargo index
+      uses: actions/cache@v1
+      with:
+        path: ~/.cargo/git
+        key: ${{ runner.os }}-cargo-index-${{ hashFiles('**/Cargo.lock') }}
+    - name: Cache cargo build
+      uses: actions/cache@v1
+      with:
+        path: target
+        key: ${{ runner.os }}-cargo-build-target-${{ hashFiles('**/Cargo.lock') }}
+
     - name: Build
       run: cargo build --release --manifest-path platform/rustboyadvance-sdl2/Cargo.toml
 
@@ -49,6 +65,22 @@ jobs:
 
     - run: rustup target add x86_64-pc-windows-msvc
 
+    - name: Cache cargo registry
+      uses: actions/cache@v1
+      with:
+        path: ~/.cargo/registry
+        key: ${{ runner.os }}-cargo-registry-${{ hashFiles('**/Cargo.lock') }}
+    - name: Cache cargo index
+      uses: actions/cache@v1
+      with:
+        path: ~/.cargo/git
+        key: ${{ runner.os }}-cargo-index-${{ hashFiles('**/Cargo.lock') }}
+    - name: Cache cargo build
+      uses: actions/cache@v1
+      with:
+        path: target
+        key: ${{ runner.os }}-cargo-build-target-${{ hashFiles('**/Cargo.lock') }}
+
     - name: Build
       run: cargo build --target x86_64-pc-windows-msvc --release --manifest-path .\platform\rustboyadvance-sdl2\Cargo.toml