* src/native/jni.hpp: We typedef the JNI types to the CACAO internal

* src/native/jni.hpp: We typedef the JNI types to the CACAO internal
types.  This should make the code smaller and more robust.
(_CLASSPATH_VM_JNI_TYPES_DEFINED): Defined.
(JNI_TYPES_ALREADY_DEFINED_IN_JNI_MD_H): Likewise.
* src/vm/global.h (java_handle_array_t): Added.
* src/vm/javaobjects.hpp: Removed all constructors with JNI types. The
constructors with the CACAO types can now be used.
* src/native/vm/openjdk/hpi.c (native/jni.hpp): Removed.
(INCLUDE_HPI_MD_H, INCLUDE_HPI_H): Added.
* tests/regression/native/checkjni.c: Likewise.
* tests/regression/native/testarguments.c: Likewise.