Check the generated icons into the build tree. This solves a couple of issues: ...

Check the generated icons into the build tree.  This solves a couple of issues:  (1) it eliminates the build dependency on ImageMagick, which was not documented and which creates a hard-to-diagnose build failure on platforms on which it isn't available, and (2) the build was completely broken on Windows, because Windows has a convert.exe program that is part of the operating system, and the TigerVNC build system was finding this and attempting to use it to generate the icons.

git-svn-id: svn://svn.code.sf.net/p/tigervnc/code/trunk@5024 3789f03b-4d11-0410-bbf8-ca57d06f2519