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