gtest: Install the run_with_tmp script for convenience

This makes it possible for other tests to utilize the script.

Change-Id: I1bb6100e4018bad020817d569294704e267c2776
Signed-off-by: William A. Kennington III <wak@google.com>
diff --git a/test/meson.build b/test/meson.build
index 1f284a5..4ebf17f 100644
--- a/test/meson.build
+++ b/test/meson.build
@@ -79,7 +79,7 @@
   foreach t : gtests
     test(
       t,
-      files('run_with_tmp.sh'),
+      run_with_tmp,
       env: {'TMPTMPL': 'stdplus-test.XXXXXXXXXX'},
       args: executable(
         t.underscorify(), t + '.cpp',