Support for java 13

[clagms]

I'm using this library in FMIMOBSTER and depend on it to support java 13.

Currently, the library gives:

2022-02-02 06:40:14:626 [main] DEBUG org.intocps.fmi.jnifmuapi.NativeFmu - Loading library: lib/Windows-amd64/fmuapi.dll
2022-02-02 06:40:14:627 [main] DEBUG org.intocps.fmi.jnifmuapi.NativeLibraryLoader - Extracting library from: lib/Windows-amd64/fmuapi.dll
2022-02-02 06:40:15:069 [main] DEBUG org.intocps.fmi.jnifmuapi.NativeLibraryLoader - Extracted library: C:\Users\au602135\AppData\Local\Temp\jnifmuapi17456685047655138051\jnifmuapi-Windows-amd64\fmuapi.dll
2022-02-02 06:40:15:069 [main] ERROR org.intocps.fmi.jnifmuapi.NativeFmu - Faild to load native Library file: lib/Windows-amd64/fmuapi.dll
java.lang.NoSuchFieldException: usr_paths
        at java.base/java.lang.Class.getDeclaredField(Class.java:2412)
        at org.intocps.fmi.jnifmuapi.NativeLibraryLoader.addLibraryPath(NativeLibraryLoader.java:153)
        at org.intocps.fmi.jnifmuapi.NativeLibraryLoader.loadLibrary(NativeLibraryLoader.java:98)
        at org.intocps.fmi.jnifmuapi.NativeFmu.<clinit>(NativeFmu.java:62)
        at org.intocps.fmi.jnifmuapi.Factory.create(Factory.java:48)

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