Improve JNI error checking to use JniAbort rather than CHECK.

Change-Id: I412d4baa76fdb6c94694bceaef3c0cfeb06a0b5b
diff --git a/src/check_jni.cc b/src/check_jni.cc
index 026dfe6..8f4e921 100644
--- a/src/check_jni.cc
+++ b/src/check_jni.cc
@@ -748,7 +748,7 @@
    */
   void CheckReleaseMode(jint mode) {
     if (mode != 0 && mode != JNI_COMMIT && mode != JNI_ABORT) {
-      JniAbortF(function_name_, "bad value for release mode: %d", mode);
+      JniAbortF(function_name_, "unknown value for release mode: %d", mode);
     }
   }