[Cin] signal handling on ppc64le

[Andrew Randrianasulu]

... I'm not a porter, yet it seems i found something relevant:

https://stackoverflow.com/questions/48526785/extract-program-counter-instruction-pointer-in-signal-handler-ppc64

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@Radu The numbered slots in the gp_regs array are just the numbered general 
purpose registers, r0 .. r31, with the functions defined by the ABI (e.g. r1 is 
the stack pointer and r2 is the TOC pointer). Of the named fields in the 
struct, ctr, link, xer, ccr, softe, mq, dar, and dsisr correspond to named 
registers in the architecture manual, and orig_gpr3, trap, and result are 
labeled with their function. That leaves only nip to be the PC. – zwol Jan 
31 '18 at 12:21
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https://elixir.bootlin.com/linux/latest/source/arch/powerpc/include/uapi/asm/ptrace.h

https://sourceforge.net/p/predef/wiki/Architectures/

so, I just defined IP = nip in bcsignals.C in if __powerpc64__ ifdef . now I 
forgot Cinelerra-GG requires python 3, time to isntall python3 ....