Adds support for Linux on Z #193

Author: deepy

src/main/kotlin/com/github/gradle/node/util/PlatformHelper.kt

@@ -25,6 +25,7 @@ open class PlatformHelper constructor(private val props: Properties = System.get
             arch == "arm" || arch.startsWith("aarch") -> property("uname")
                 .mapIf({ it == "armv8l" || it == "aarch64" }) { "arm64" }
             arch == "ppc64le" -> "ppc64le"
+            arch == "s390x" -> "s390x"
             arch.contains("64") -> "x64"
             else -> "x86"
         }

src/test/groovy/com/github/gradle/node/util/PlatformHelperTest.groovy

@@ -32,6 +32,7 @@ class PlatformHelperTest extends Specification {
         'Linux'     | 'x86'     | 'linux'  | 'x86'     | false
         'Linux'     | 'x86_64'  | 'linux'  | 'x64'     | false
         'Linux'     | 'ppc64le' | 'linux'  | 'ppc64le' | false
+        'Linux'     | 's390x'   | 'linux'  | 's390x'   | false
         'SunOS'     | 'x86'     | 'sunos'  | 'x86'     | false
         'SunOS'     | 'x86_64'  | 'sunos'  | 'x64'     | false
     }