* i386-linux-tdep.c (FRAMELESS_SIGNAL): Moved here from

* i386-linux-tdep.c (FRAMELESS_SIGNAL): Moved here from
config/i386/nm-linux.h (including comment).
(i386_linux_frame_chain): New function implementing guts of the
former FRAME_CHAIN macro, but using read_memory_unsigned_integer
instead of read_memory_integer.
(i386_linux_frame_saved_pc): Removed doc pointing to
i386/tm-linux.h for an explanation of FRAMELESS_SIGNAL since that
now lives in this file.
* config/i386/tm-linux.h (FRAMELESS_SIGNAL): Moved to
i386-linux-tdep.c (including comment).
(FRAME_CHAIN): Redefined in terms of i386_linux_frame_chain.
(i386_linux_frame_chain): New prototype.