Bug 425159: properly support optional help viewer (--enable-help-viewer), r=neil, sr=bsmedberg

config/autoconf.mk.in

@@ -159,7 +159,8 @@ MOZ_NO_XPCOM_OBSOLETE = @MOZ_NO_XPCOM_OBSOLETE@
 MOZ_NO_FAST_LOAD = @MOZ_NO_FAST_LOAD@
 NS_PRINTING = @NS_PRINTING@
 MOZ_CRASHREPORTER = @MOZ_CRASHREPORTER@
-MOZ_MOCHITEST = @MOZ_MOCHITEST@ 
+MOZ_MOCHITEST = @MOZ_MOCHITEST@
+MOZ_HELP_VIEWER = @MOZ_HELP_VIEWER@
 
 MOZ_JAVAXPCOM = @MOZ_JAVAXPCOM@
 JAVA_INCLUDE_PATH="@JAVA_INCLUDE_PATH@"

configure.in

@@ -4281,6 +4281,7 @@ MOZ_PYTHON_VER_DOTTED=
 MOZ_RDF=1
 MOZ_REFLOW_PERF=
 MOZ_SAFE_BROWSING=
+MOZ_HELP_VIEWER=
 MOZ_SPELLCHECK=1
 MOZ_STATIC_MAIL_BUILD=
 MOZ_STORAGE=1
@@ -5854,6 +5855,17 @@ fi
 
 AC_SUBST(MOZ_NATIVE_SQLITE)
 
+dnl = Enable help viewer (off by default)
+dnl ========================================================
+MOZ_ARG_ENABLE_BOOL(help-viewer,
+[  --enable-help-viewer        Enable help viewer],
+    MOZ_HELP_VIEWER=1,
+    MOZ_HELP_VIEWER= )
+if test -n "$MOZ_HELP_VIEWER"; then
+     AC_DEFINE(MOZ_HELP_VIEWER)
+fi
+AC_SUBST(MOZ_HELP_VIEWER)
+
 dnl ========================================================
 dnl = Enable safe browsing (anti-phishing)
 dnl ========================================================