runtime: handle Alpha GNU/Linux in getSiginfo

    
    Patch by Uros Bizjak.
    
    Reviewed-on: https://go-review.googlesource.com/51370

From-SVN: r250588

gcc/go/gofrontend/MERGE

-61ce3b80ab20cb1f16960c1784bc0937abaa440a
+feb26fbb5065eadfe1f8610e9b74b3749a87c52d
 
 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 __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;