Remove base_dir since not support by old rubies

The next `Dir.glob` in the gemspec does not use the `base_dir` argument,
so if people are reading this gemspec from another folder, it's giving
the correct list of files anyways?

I can probably add compatibility code for this anyways, I just want to
confirm this is the culprit for now.

Author: deivid-rodriguez

bundler.gemspec

@@ -47,8 +47,7 @@ Gem::Specification.new do |s|
   s.add_development_dependency "rspec",      "~> 3.6"
   s.add_development_dependency "rubocop",    "= 0.50.0"
 
-  base_dir = File.dirname(__FILE__).gsub(%r{([^A-Za-z0-9_\-.,:\/@\n])}, "\\\\\\1")
-  s.files = Dir.glob("{lib,exe}/**/*", File::FNM_DOTMATCH, :base => base_dir).reject {|f| File.directory?(File.expand_path(f, base_dir)) }
+  s.files = Dir.glob("{lib,exe}/**/*", File::FNM_DOTMATCH).reject {|f| File.directory?(f) }
 
   # we don't check in man pages, but we need to ship them because
   # we use them to generate the long-form help for each command.

spec/quality_spec.rb

@@ -242,13 +242,15 @@ def check_for_specific_pronouns(filename)
   end
 
   it "ships the correct set of files" do
-    base_dir = File.dirname(__dir__).gsub(%r{([^A-Za-z0-9_\-.,:\/@\n])}, "\\\\\\1")
-    git_list = IO.popen("git -C #{base_dir} ls-files -z", &:read).split("\x0").select {|f| f.match(%r{^(lib|exe)/}) }
-    git_list += %w[CHANGELOG.md LICENSE.md README.md bundler.gemspec]
+    Dir.chdir(root) do
+      git_list = IO.popen("git ls-files -z", &:read).split("\x0").select {|f| f.match(%r{^(lib|exe)/}) }
+      git_list += %w[CHANGELOG.md LICENSE.md README.md bundler.gemspec]
+      git_list += Dir.glob("man/**/*")
 
-    gem_list = Gem::Specification.load(gemspec.to_s).files
+      gem_list = Gem::Specification.load(gemspec.to_s).files
 
-    expect(git_list.to_set).to eq(gem_list.to_set)
+      expect(git_list.to_set).to eq(gem_list.to_set)
+    end
   end
 
   it "does not contain any warnings" do