Enable linux thread support on the alpha.  The guts of linux_clone was mainly cut-n-pasted from the i386 port, except for the method of setting the child's stack which is the only MD part of this function.
Enable linux thread support on the alpha.  The guts of linux_clone was
mainly cut-n-pasted from the i386 port, except for the method of setting
the child's stack which is the only MD part of this function.

I've tested with the example apps shipped with the linux threads source
code (ex1-ex6) and with several binary builds of Mozilla.

jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase