Change to use installed diffimg in rtest.sh

diff --git a/rtest/rtest.sh b/rtest/rtest.sh
index 184c2f30d8f06fcfd6969806eb3d6f1a15d58e1c..78837da78a3555b8d1bdd0d1f8d82acb2df32579 100755 (executable)
--- a/rtest/rtest.sh
+++ b/rtest/rtest.sh
@@ -28,7 +28,7 @@ GENERATE=              # If set, generate test data
 VERBOSE=               # If set, give verbose output
 NOOP=                  # If set, just print list of tests
 DOT=${DOT-$(whence dot)} # should be $(top_builddir)/cmd/dot/dot_static
-DIFFIMG=../contrib/diffimg/diffimg # build tree version
+DIFFIMG=${DIFFIMG-$(whence diffimg)}
 
 TESTNAME=   # name of test
 GRAPH=      # graph specification