Fix hypotl to C99 specification.

Fix hypotl to return +infinity when either component is an infinity, even
when the other is NaN, as specified in Annex F.9.4.3 of C99-TC3.

mingw-w64-crt/ChangeLog:
2010-06-27  Doug Semler <dougsemler@gmail.com>

	* math/hypotl (hypotl): Return +infinity when either of the inputs
	  is an infinity, including when the other is NaN (Annex F.9.4.3)

git-svn-id: svn+ssh://svn.code.sf.net/p/mingw-w64/code/trunk@2668 4407c894-4637-0410-b4f5-ada5f102cad1