tor/changes/double-0-check

  o Build improvements (bizarre platform detection):
    - Try to detect it if we are ever building on a platform where
      memset(...,0,...) does not set the value of a double to 0.0.  Such
      platforms are permitted by the C standard, though in practice
      they're pretty rare (since IEEE 754 is nigh-ubiquitous). We don't
      currently support them, but it's better to detect them and fail
      than to perform erroneously.
Detect platforms where memset(0) doesn't set doubles to 0.0. This is allowed by the C statndard, which permits you to represent doubles any way you like, but in practice we have some code that assumes that memset() clears doubles in structs. Noticed as part of 7802 review; see 8081 for more info. 2013-01-29 23:38:15 +01:00			`o Build improvements (bizarre platform detection):`
			`- Try to detect it if we are ever building on a platform where`
			`memset(...,0,...) does not set the value of a double to 0.0. Such`
			`platforms are permitted by the C standard, though in practice`
			`they're pretty rare (since IEEE 754 is nigh-ubiquitous). We don't`
			`currently support them, but it's better to detect them and fail`
			`than to perform erroneously.`