Revert "Temporary remove all -Werror flags"

This reverts commit 89c09214eeed951684405c10c233304834a89beb.

kotlin-native/Interop/Indexer/build.gradle

@@ -143,8 +143,8 @@ kotlinNativeInterop {
 
 compileKotlin {
     kotlinOptions {
-//        allWarningsAsErrors=true
+        allWarningsAsErrors=true
-	    freeCompilerArgs = ["-Xskip-prerelease-check"]
+	kotlinOptions.freeCompilerArgs = ["-Xskip-prerelease-check"]
     }
 }
 

kotlin-native/Interop/Runtime/build.gradle

@@ -77,7 +77,7 @@ compileKotlin {
     kotlinOptions {
         freeCompilerArgs = ['-Xuse-experimental=kotlin.ExperimentalUnsignedTypes', '-Xuse-experimental=kotlin.Experimental',
                             '-Xopt-in=kotlin.RequiresOptIn', "-XXLanguage:+InlineClasses", "-Xskip-prerelease-check"]
-//        allWarningsAsErrors=true
+        allWarningsAsErrors=true
     }
 }
 

kotlin-native/Interop/StubGenerator/build.gradle

@@ -47,6 +47,6 @@ dependencies {
 compileKotlin {
     kotlinOptions {
         freeCompilerArgs = ['-Xopt-in=kotlin.ExperimentalUnsignedTypes', '-Xskip-metadata-version-check']
-//        allWarningsAsErrors=true
+        allWarningsAsErrors=true
     }
 }

kotlin-native/backend.native/build.gradle

@@ -56,7 +56,7 @@ compileCompilerKotlin {
     // but not for Kotlin.
     dependsOn('generateCompilerProto')
     kotlinOptions.jvmTarget = "1.8"
-//    kotlinOptions.allWarningsAsErrors=true
+    kotlinOptions.allWarningsAsErrors=true
     kotlinOptions.freeCompilerArgs += ['-Xopt-in=kotlin.RequiresOptIn', '-Xopt-in=org.jetbrains.kotlin.ir.ObsoleteDescriptorBasedAPI', '-Xskip-prerelease-check']
 }