* infrun.c, infcmd.c, breakpoint.c, main.c, symfile.c,

* infrun.c, infcmd.c, breakpoint.c, main.c, symfile.c,
breakpoint.h, tm-sun4os4.h, tm-sparc.h, sparc-tdep.c, tm-mips.h,
mips-tdep.h, tm-sun3.h, tm-68k.h, m68k-tdep.h:  Add support for
stepping (and nexting) through longjmp().  Also, cleanup
breakpoint handling quite a bit by creating explicit breakpoint
types instead of using magic breakpoint numbers.
Makefile.in:  Update version to 4.4.3