Bug 1411462 - Add test for `configure --help`; r=glandium

We add a simple cram test that `configure --help` works.

I added the test to build/tests because I'm not sure where else it should go.

This test uncovers a few interesting things:

1) piping `./configure --help` to `head` directly causes a Python
   traceback (presumably due to the pipe disappearing once N lines
   have been read)
2) "checking for vcs source checkout" is printed for --help
3) It is printed twice (!!)

These will be addressed later. Establishing test coverage is
more important.

MozReview-Commit-ID: 9zQ5X8ulTkc

--HG--
extra : rebase_source : aaf660152cdfe37580f559976bca13ea9bf14c49

build/moz.build

@@ -15,6 +15,10 @@ if CONFIG['OS_ARCH'] == 'WINNT':
 else:
     DIRS += ['unix']
 
+CRAMTEST_MANIFESTS += [
+    'tests/cram/cram.ini',
+]
+
 if CONFIG['MOZ_WIDGET_TOOLKIT'] == 'android':
     DIRS += ['annotationProcessors']
 

build/tests/cram/cram.ini

@@ -0,0 +1 @@
+[test_configure_help.t]

build/tests/cram/test_configure_help.t

@@ -0,0 +1,15 @@
+configure --help works
+
+  $ cd $TESTDIR/../../..
+
+  $ touch $TMP/mozconfig
+  $ export MOZCONFIG=$TMP/mozconfig
+  $ ./configure --help > out
+  $ head -n 7 out
+  Adding configure options from */tmp/mozconfig (glob)
+  checking for vcs source checkout... hg
+  checking for vcs source checkout... hg
+  Usage: configure.py [options]
+  
+  Options: [defaults in brackets after descriptions]
+    --help                    print this message