Fix x86_64-pc-windows-gnu cross compilation

Author: khvzak

.github/workflows/main.yml

@@ -13,6 +13,7 @@ jobs:
           - mips64-unknown-linux-gnuabi64
           - x86_64-apple-darwin
           - aarch64-apple-darwin
+          - x86_64-pc-windows-gnu
           - x86_64-pc-windows-msvc
         include:
           - target: x86_64-unknown-linux-gnu
@@ -25,6 +26,8 @@ jobs:
             os: macos-latest
           - target: aarch64-apple-darwin
             os: macos-latest
+          - target: x86_64-pc-windows-gnu
+            os: ubuntu-22.04
           - target: x86_64-pc-windows-msvc
             os: windows-latest
     steps:
@@ -46,6 +49,12 @@ jobs:
           sudo apt-get update -y
           sudo apt-get install -y --no-install-recommends gcc-mips64-linux-gnuabi64 libc6-dev-mips64-cross
         shell: bash
+      - name: Install GCC (x86_64-pc-windows-gnu)
+        if: ${{ matrix.target == 'x86_64-pc-windows-gnu' }}
+        run: |
+          sudo apt-get update -y
+          sudo apt-get install -y --no-install-recommends gcc-mingw-w64-x86-64
+        shell: bash
       - name: Build for ${{ matrix.target }}
         run: |
           cargo build --manifest-path testcrate/Cargo.toml --target ${{ matrix.target }} --release

src/lib.rs

@@ -106,6 +106,12 @@ impl Build {
             "aarch64-apple-darwin" => {
                 make.env("MACOSX_DEPLOYMENT_TARGET", "11.0");
             }
+            _ if target.contains("linux") => {
+                make.env("TARGET_SYS", "Linux");
+            }
+            _ if target.contains("windows") => {
+                make.env("TARGET_SYS", "Windows");
+            }
             _ => {}
         }