Fixes PR52.

Fixes PR52.
* src/vm/array.c (array_objectarray_element_set): Use
builtin_canstore.

* .hgignore (tests/regression/assertion/*.class)
(tests/regression/assertion/packagetest/*.class)
(tests/regression/bugzilla/*.class): Added.
* configure.ac (AC_CONFIG_FILES): Added
tests/regression/bugzilla/Makefile.
* tests/regression/Makefile.am (SUBDIRS): Added bugzilla.
* tests/regression/bugzilla/All.java: New file.
* tests/regression/bugzilla/Makefile.am: Likewise.
* tests/regression/bugzilla/PR52.java: Likewise.