Drop mingw support in GSL module

.github/workflows/gradle.yml

@@ -73,10 +73,7 @@ jobs:
         uses: actions/setup-java@v1
         with:
           java-version: 11
-      - name: Install mingw-w64-x86_64-gsl
-        run: c:\msys64\usr\bin\pacman --noconfirm -S mingw-w64-x86_64-gsl
       - name: Add msys to path
-        # msys installed on default image but not in path
         run: SETX PATH "%PATH%;C:\msys64\mingw64\bin"
       - name: Cache gradle
         uses: actions/cache@v2
@@ -96,4 +93,4 @@ jobs:
           key: ${{ runner.os }}-konan-1.4.20-eap-37
           restore-keys: ${{ runner.os }}-konan-1.4.20-eap-37
       - name: Build with Gradle
-        run: ./gradlew --build-cache :kmath-gsl:cinteropLibgslNative build
+        run: ./gradlew --build-cache build

kmath-gsl/build.gradle.kts

@@ -5,13 +5,13 @@ plugins {
 }
 
 kotlin {
-    val hostOs = System.getProperty("os.name")
-
-    val nativeTarget = when {
-        hostOs == "Mac OS X" -> macosX64("native")
-        hostOs == "Linux" -> linuxX64("native")
-        hostOs.startsWith("Windows") -> mingwX64("native")
-        else -> throw GradleException("Host OS is not supported in Kotlin/Native.")
+    val nativeTarget = when (System.getProperty("os.name")) {
+        "Mac OS X" -> macosX64("native")
+        "Linux" -> linuxX64("native")
+        else -> {
+            logger.warn("Current OS cannot build any of kmath-gsl targets.")
+            return@kotlin
+        }
     }
 
     val main by nativeTarget.compilations.getting {