Fix //tools/jdk:gen_platformclasspath target on MacOSX
MacOSX's `mktemp` command requires the template parameter.
Closes
@@ -193,7 +193,7 @@ genrule(
outs = ["platformclasspath-impl.jar"],
cmd = """
set -eu
-TMPDIR=$$(mktemp -d)
+TMPDIR=$$(mktemp -d -t tmp.XXXXXXXX)
$(JAVABASE)/bin/javac $< -d $$TMPDIR
$(JAVA) -cp $$TMPDIR DumpPlatformClassPath 8 $@
rm -rf $$TMPDIR
