avoid polling for changes on BSD

Gemfile

@@ -13,3 +13,8 @@ platforms :mingw, :x64_mingw, :mswin, :jruby do
 end
 
 gem "wdm", "~> 0.1.1", :platforms => [:mingw, :x64_mingw, :mswin]
+
+require 'rbconfig'
+if RbConfig::CONFIG['target_os'] =~ /(?i-mx:bsd|dragonfly)/
+  gem 'rb-kqueue', '>= 0.2'
+end

Gemfile.lock

@@ -9,10 +9,10 @@ GEM
       eventmachine (>= 0.12.9)
       http_parser.rb (~> 0.6.0)
     eventmachine (1.2.7)
-    ffi (1.14.2)
+    ffi (1.15.0)
     forwardable-extended (2.6.0)
     http_parser.rb (0.6.0)
-    i18n (1.8.8)
+    i18n (1.8.10)
       concurrent-ruby (~> 1.0)
     jekyll (4.2.0)
       addressable (~> 2.4)
@@ -37,12 +37,12 @@ GEM
       jekyll (>= 3.8, < 5.0)
     jekyll-watch (2.2.1)
       listen (~> 3.0)
-    kramdown (2.3.0)
+    kramdown (2.3.1)
       rexml
     kramdown-parser-gfm (1.1.0)
       kramdown (~> 2.0)
     liquid (4.0.3)
-    listen (3.4.1)
+    listen (3.5.1)
       rb-fsevent (~> 0.10, >= 0.10.3)
       rb-inotify (~> 0.9, >= 0.9.10)
     mercenary (0.4.0)
@@ -52,7 +52,9 @@ GEM
     rb-fsevent (0.10.4)
     rb-inotify (0.10.1)
       ffi (~> 1.0)
-    rexml (3.2.4)
+    rb-kqueue (0.2.6)
+      ffi (>= 0.5.0)
+    rexml (3.2.5)
     rouge (3.26.0)
     safe_yaml (1.0.5)
     sassc (2.4.0)
@@ -68,9 +70,10 @@ DEPENDENCIES
   jekyll (~> 4.2.0)
   jekyll-feed (~> 0.12)
   jekyll-seo-tag (~> 2.7)
+  rb-kqueue (>= 0.2)
   tzinfo (~> 1.2)
   tzinfo-data
   wdm (~> 0.1.1)
 
 BUNDLED WITH
-   2.2.9
+   2.2.16