Associate .x extension to Linker Script language (#4040)

lib/linguist/heuristics.rb

@@ -518,6 +518,8 @@ module Linguist
         Language["RPC"]
       elsif /^%(end|ctor|hook|group)\b/.match(data)
         Language["Logos"]
+      elsif /OUTPUT_ARCH\(|OUTPUT_FORMAT\(|SECTIONS/.match(data)
+        Language["Linker Script"]
       end
     end
 

lib/linguist/languages.yml

@@ -2365,6 +2365,7 @@ Linker Script:
   extensions:
   - ".ld"
   - ".lds"
+  - ".x"
   filenames:
   - ld.script
   tm_scope: none