Add missing prereq.


git-svn-id: svn://svn.valgrind.org/valgrind/trunk@13618 a5019735-40e9-0310-863c-91ae7b9d1cf9
diff --git a/memcheck/tests/amd64/insn-pcmpistri.vgtest b/memcheck/tests/amd64/insn-pcmpistri.vgtest
index 225c725..5bbe79f 100644
--- a/memcheck/tests/amd64/insn-pcmpistri.vgtest
+++ b/memcheck/tests/amd64/insn-pcmpistri.vgtest
@@ -1,2 +1,3 @@
+prereq: test -e ./insn-pcmpistri
 prog: insn-pcmpistri
 vgopts: -q