The program counter calculation from pt_regs is the only portion of profile
accounting that differs across various architectures.  This is usually
instruction_pointer(regs), but to handle the few arches where it isn't,
introduce profile_pc().
Signed-off-by: William Irwin <wli@holomorphy.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>