tests: Trim .nim files trailing whitespace

via OSX: find . -name '*.nim' -exec sed -i '' -E 's/[[:space:]]+$//' {} +

tests/casestmt/tlinearscanend.nim

@@ -4,13 +4,13 @@ import strutils
 var x = 343
 
 case stdin.readline.parseInt
-of 0: 
+of 0:
   echo "most common case"
-of 1: 
+of 1:
   {.linearScanEnd.}
   echo "second most common case"
 of 2: echo "unlikely: use branch table"
-else: 
+else:
   echo "unlikely too: use branch table"
 
 
@@ -18,7 +18,7 @@ case x
 of 23: echo "23"
 of 343: echo "343"
 of 21: echo "21"
-else: 
+else:
   {.linearScanEnd.}
   echo "default"