Added missing files to Win32 build.
Added missing files to Win32 build.

* svnadmin/svnadmin.dsp: Added shell.c and svnadmin.h.

jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion