A follow-up to r21531 (and correction to r21845), updating our minimum build-time Neon version.
A follow-up to r21531 (and correction to r21845), updating our minimum
build-time Neon version.

* INSTALL
  Regardless of which version of Neon is used at runtime, Subversion
  should be built against Neon 0.26.1+ (on Windows, at least) to
  support the "http-auth-types" configuration option.  The "negotiate"
  auth type allows GSSAPI/SSPI to be enabled or disabled on Windows.

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