runtime: handle PPC/PPC64 GNU/Linux in getSiginfo

    
    Updates golang/go#20931
    
    Reviewed-on: https://go-review.googlesource.com/50631

From-SVN: r250436

gcc/go/gofrontend/MERGE

-e34cb8dee6c1f215329e0eea79202b48cb83817c
+a9f1aeced86691de891fbf2a8c97e848faf1962e
 
 The first line of this file holds the git revision number of the last
 merge done from the gofrontend repository.

libgo/runtime/go-signal.c

@@ -215,6 +215,11 @@ getSiginfo(siginfo_t *info, void *context __attribute__((unused)))
 	ret.sigpc = ((ucontext_t*)(context))->uc_mcontext.gregs[REG_EIP];
   #endif
 #endif
+#ifdef __PPC__
+  #ifdef __linux__
+	ret.sigpc = ((ucontext_t*)(context))->uc_mcontext.regs->nip;
+  #endif
+#endif
 
 	if (ret.sigpc == 0) {
 		// Skip getSiginfo/sighandler/sigtrampgo/sigtramp/handler.