Fix cproj to project z back to z.

The C99 standard specifies that z projects to z, except for complex
infinities.  This fixes the implementation to project to z directly
back to z, rather than stereographically.

mingw-w64-crt/ChangeLog:
2010-07-05  Doug Semler  <dougsemler@gmail.com>

	* complex/cproj.def.h (cproj): Project z back to z, rather than
	  stereographically.

git-svn-id: svn+ssh://svn.code.sf.net/p/mingw-w64/code/trunk@2781 4407c894-4637-0410-b4f5-ada5f102cad1