NO BUG - Change Sphinx path for build system docs to work around a silly URL firewall

--HG--
extra : rebase_source : cb010c0986603c83d47912876ee401027eea4771

build/moz.build

@@ -4,7 +4,8 @@
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
-SPHINX_TREES['build'] = 'docs'
+# This cannot be named "build" because of bug 922191.
+SPHINX_TREES['buildsystem'] = 'docs'
 
 if CONFIG['OS_ARCH'] not in ('WINNT', 'OS2'):
     DIRS += ['unix']