Fix bugs in the initialization of the ISA-L library JNI bindings

Stack: [0x00007f2b9d405000,0x00007f2b9d506000],  sp=0x00007f2b9d504748,  free space=1021k
Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code)
V  [libjvm.so+0xa90c90]  UTF8::unicode_length(char const*)+0x0
V  [libjvm.so+0x6ddfc3]  jni_NewStringUTF+0xc3
j  org.apache.hadoop.io.erasurecode.ErasureCodeNative.getLibraryName()Ljava/lang/String;+0
j  org.apache.hadoop.util.NativeLibraryChecker.main([Ljava/lang/String;)V+212
v  ~StubRoutines::call_stub
V  [libjvm.so+0x68c616]  JavaCalls::call_helper(JavaValue*, methodHandle*, JavaCallArguments*, Thread*)+0x1056
V  [libjvm.so+0x6cdc32]  jni_invoke_static(JNIEnv_*, JavaValue*, _jobject*, JNICallType, _jmethodID*, JNI_ArgumentPusher*, Thread*)+0x362
V  [libjvm.so+0x6ea63a]  jni_CallStaticVoidMethod+0x17a
C  [libjli.so+0x7bcc]  JavaMain+0x80c
C  [libpthread.so.0+0x8182]  start_thread+0xc2

Java frames: (J=compiled Java code, j=interpreted, Vv=VM code)
j  org.apache.hadoop.io.erasurecode.ErasureCodeNative.getLibraryName()Ljava/lang/String;+0
j  org.apache.hadoop.util.NativeLibraryChecker.main([Ljava/lang/String;)V+212
v  ~StubRoutines::call_stub