[PATCH] Use read_memory_unsigned_integer when reading to CORE_ADDR

[Andrew Cagney]

>    /* Don't cause a memory_error when accessing sigcontext in case the stack
>       layout has changed or the stack is corrupt.  */
>    target_read_memory (sigcontext_addr + SIGCONTEXT_PC_OFFSET, buf, ptrbytes);
> -  return extract_unsigned_integer (buf, ptrbytes);
> +  return extract_typed_address (buf, builtin_type_void_data_ptr);

This should be builtin_type_void_code_ptr since it is extracting a code 
pointer (the PC).  It, also, might as well use read_memory_typed_address().

Andrew