Prevent a warning: `*' interpreted as argument prefix

Author: mame

test/rubygems/test_gem_ext_cargo_builder/rust_ruby_example/build.rb

@@ -15,7 +15,7 @@
 
 Dir.mktmpdir("rust_ruby_example") do |dir|
   built_gem = File.expand_path(File.join(dir, "rust_ruby_example.gem"))
-  system *gem, "build", gemspec, "--output", built_gem
-  system *gem, "install", "--verbose", "--local", built_gem, *ARGV
+  system(*gem, "build", gemspec, "--output", built_gem)
+  system(*gem, "install", "--verbose", "--local", built_gem, *ARGV)
   system %q(ruby -rrust_ruby_example -e "puts 'Result: ' + RustRubyExample.reverse('hello world')")
 end