[PATCH, alpha]: libgo patch: also recognize alpha in signal handler

[Uros Bizjak]

Similar patch to the one for PPC [1].

[1] https://gcc.gnu.org/ml/gcc-patches/2017-07/msg01334.html

Tested on alphaev68-pc-linux-gnu.

Uros.

Index: libgo/runtime/go-signal.c
===================================================================
--- libgo/runtime/go-signal.c   (revision 250443)
+++ libgo/runtime/go-signal.c   (working copy)
@@ -215,6 +215,11 @@
        ret.sigpc = ((ucontext_t*)(context))->uc_mcontext.gregs[REG_EIP];
   #endif
 #endif
+#ifdef __alpha__
+  #ifdef __linux__
+       ret.sigpc = ((ucontext_t*)(context))->uc_mcontext.sc_pc;
+  #endif
+#endif
 #ifdef __PPC__
   #ifdef __linux__
        ret.sigpc = ((ucontext_t*)(context))->uc_mcontext.regs->nip;