ruby-runner.c.in: ignore empty env

* template/ruby-runner.c.in (main): ignore empty or separator-only
  value.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@52035 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

template/ruby-runner.c.in

@@ -14,6 +14,9 @@ main(int argc, char **argv)
     static const char builddir[] = BUILDDIR;
     const char *libpath = getenv(LIBPATHENV);
     if (libpath) {
+	while (*libpath == PATH_SEP) ++libpath;
+    }
+    if (libpath && *libpath) {
 	size_t n = strlen(libpath);
 	char *e = malloc(sizeof(builddir)+n+1);
 	memcpy(e, builddir, sizeof(builddir)-1);