Android: statically load iconv library

Fixes #3291

Thanks to @arpruss for reporting the bug, and suggesting the fix.

Also, remove trailing whitespaces.

build/android/src/net/minetest/minetest/MtNativeActivity.java

@@ -87,6 +87,7 @@ public class MtNativeActivity extends NativeActivity {
 		System.loadLibrary("ssl");
 		System.loadLibrary("crypto");
 		System.loadLibrary("gmp");
+		System.loadLibrary("iconv");
 
 		// We don't have to load libminetest.so ourselves,
 		// but if we do, we get nicer logcat errors when