port r9740 from 1.1 branch: Bump effective version to tarball version of 1.1 release

STARPU-VERSION

@@ -18,7 +18,7 @@
 #   public release, then set age to 0. change
 
 # This is the tarball version, major.minor
-STARPU_EFFECTIVE_VERSION=1.0
+STARPU_EFFECTIVE_VERSION=1.1
 
 # Note for StarPU 1.1: we have changed ABI