avoid use of vasnprintf in base/error.c
avoid use of vasnprintf in base/error.c

commit c94f299fc8e602912a7d68c57404a96b98da4037 uses vasnprintf
which was previously removed from the libheimbase directory in
order to prevent a dependency on libroken.

Replace vasnprintf with snprintf and malloc to avoid the
dependency.

Change-Id: I029e7e6883406ca7311490a3dab4b65cad3ba70b

madscientist159/heimdal,madscientist159/heimdal,madscientist159/heimdal,madscientist159/heimdal,madscientist159/heimdal,madscientist159/heimdal,madscientist159/heimdal