Moved some classes around.

src/main/java/net/rubygrapefruit/platform/internal/DefaultProcess.java

@@ -0,0 +1,11 @@
+package net.rubygrapefruit.platform.internal;
+
+import net.rubygrapefruit.platform.*;
+import net.rubygrapefruit.platform.internal.jni.PosixProcessFunctions;
+
+public class DefaultProcess implements net.rubygrapefruit.platform.Process {
+    @Override
+    public int getProcessId() throws NativeException {
+        return PosixProcessFunctions.getPid();
+    }
+}