Adjust Jamfile to fix dependencies.

3DRendering wasn't depending on the mesa headers as needed, so its
build would break in a multi-job jam if mesa hadn't already been
downloaded.

src/preferences/3drendering/Jamfile

@@ -2,14 +2,14 @@ SubDir HAIKU_TOP src preferences 3drendering ;
 SubDirSysHdrs $(HAIKU_MESA_HEADERS) ;
 
 # For GCC2
-if $(HAIKU_GCC_VERSION[1]) < 3 { 
+if $(HAIKU_GCC_VERSION[1]) < 3 {
 	SubDirC++Flags --no-warnings ;
 }
 
 
 UsePrivateHeaders interface ;
 
-Preference 3DRendering :
+local sources =
 	OpenGLApp.cpp
 	OpenGLWindow.cpp
 	OpenGLView.cpp
@@ -18,6 +18,14 @@ Preference 3DRendering :
 	ExtensionsView.cpp
 	InfoView.cpp
 	LogoView.cpp
+	;
+
+Includes [ FGristFiles $(sources) ] : $(HAIKU_MESA_HEADERS_DEPENDENCY) ;
+	# Dependency needed to trigger downloading/unzipping the package before
+	# compiling the files.
+
+Preference 3DRendering
+	: $(sources)
 	: be GL translation libcolumnlistview.a $(HAIKU_LOCALE_LIBS)
 		$(TARGET_LIBSUPC++)
 	: 3DRendering.rdef
@@ -32,4 +40,4 @@ DoCatalogs 3DRendering :
 	InfoView.cpp
 	OpenGLWindow.cpp
 ;
-	
+