Add ability to specify the Zstd temp folder with a property

The new property is `ZstdTempFolder` and it is used to extract the
native library and load it from there.

Addresses: #315

src/main/java/com/github/luben/zstd/util/Native.java

@@ -13,6 +13,7 @@ public enum Native {
  ;
 
  private static final String nativePathOverride = "ZstdNativePath";
+ private static final String tempFolderOverride = "ZstdTempFolder";
  private static final String libnameShort = "zstd-jni-" + ZstdVersion.VERSION;
  private static final String libname = "lib" + libnameShort;
  private static final String errorMsg = "Unsupported OS/arch, cannot find " +
@@ -83,7 +84,12 @@ public Void run() {
  }
 
  public static synchronized void load() {
- load(null);
+ String tempFolder = System.getProperty(tempFolderOverride);
+ if (tempFolder == null) {
+ load(null);
+ } else {
+ load(new File(tempFolder));
+ }
  }
 
  public static synchronized void load(final File tempFolder) {