webkit_gtk: Use ninja instead of make.
webkit_gtk: Use ninja instead of make.

Let's see if this fixes out-of-memory problems on the buildmaster...
Begasus/haikuports,haikuports/haikuports,haikuports/haikuports,Begasus/haikuports,Begasus/haikuports,haikuports/haikuports,Begasus/haikuports,Begasus/haikuports,haikuports/haikuports,haikuports/haikuports