libgcj.spec.in: Use THREADSTARTFILESPEC to affect the spec for startfile.

libgcj.spec.in: Use THREADSTARTFILESPEC to affect the spec for startfile.

	* libgcj.spec.in: Use THREADSTARTFILESPEC to affect the spec for
	startfile.
	* configure.ac: Allow targets to affect the spec for startfile
	by specifying a THREADSTARTFILESPEC variable.  Define this for
	the win32 threads package to include crtmt.o.
	* configure: Regenerate.
	* win32.cc (_CRT_MT): Remove definition.
	(__mingwthr_key_dtor): Likewise.

Co-Authored-By: Danny Smith <dannysmith@users.sourceforge.net>
From-SVN: r115196