inferior_fp_registers by reading them from the inferior before
modifying and writing them back.
Fixes unexplainable inferior FP exceptions after calls to the inferior
or setting of floating point registers.
* mips-tdep.c (mips_skip_prologue): Skip move of argument register
to register which is generated by gcc-2.4.
* nat-sparc.c -> sparc-nat.c
* nat-sun4os4.h -> nm-sun4os4.h
* nat-trash.h -> nm-trash.h
* configure.in: link to nm.h rather than nat.h.
* infptrace.c: include nm.h rather than nat.h.