If server fails to create a thread because of lack-of-resources (EAGAIN),...

If server fails to create a thread because of lack-of-resources (EAGAIN), don't terminate.  Keep serving... Memory may become available again later.  From Kate.

git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@5191 42af7a65-404d-4744-a932-0658087f49c3