re PR classpath/23863 (mprec buffer overwrite bug)

re PR classpath/23863 (mprec buffer overwrite bug)

	PR classpath/23863:
	* native/fdlibm/dtoa.c (_dtoa): Free contents of _Jv_reent when
	finished.
	* native/fdlibm/mprec.c: New version from newlib.  Commented out
	some includes.  Added <assert.h>.
	(_reent, _Bigint): New defines.
	(_REENT_CHECK_MP, _REENT_MP_FREELIST, _REENT_MP_P5S): Likewise.
	(__ULong, __Long): New types.
	(_calloc_r): New function.
	(Balloc): Dynamically add new _freelist entries as needed.
	* native/fdlibm/mprec.h (struct _Jv_Bigint): Don't use
	MAX_BIGNUMS to size _x[].
	(struct _Jv_reent): _freelist now a _Jv_Bigint**.  Removed
	_allocation_map, num.  Added _max_k.

From-SVN: r114511