Fix whitespace issues found by git diff --check, add gitattributes

Set per file type attributes in .gitattributes to fine-tune whitespace
checks.  With the associated cleanups, the tree is now clean for git

doc/src/sgml/event-trigger.sgml

@@ -793,9 +793,9 @@ CREATE EVENT TRIGGER noddl ON ddl_command_start
 <screen>
 =# \dy
                      List of event triggers
- Name  |       Event       | Owner | Enabled | Procedure | Tags 
+ Name  |       Event       | Owner | Enabled | Procedure | Tags
 -------+-------------------+-------+---------+-----------+------
- noddl | ddl_command_start | dim   | enabled | noddl     | 
+ noddl | ddl_command_start | dim   | enabled | noddl     |
 (1 row)
 
 =# CREATE TABLE foo(id serial);

doc/src/sgml/func.sgml

@@ -13469,7 +13469,7 @@ SELECT * FROM unnest2(ARRAY[[1,2],[3,4]]);
 <programlisting>
 -- set returning function WITH ORDINALITY
 SELECT * FROM pg_ls_dir('.') WITH ORDINALITY AS t(ls,n);
-       ls        | n  
+       ls        | n
 -----------------+----
  pg_serial       |  1
  pg_twophase     |  2

doc/src/sgml/pgbench.sgml

@@ -439,7 +439,7 @@ pgbench <optional> <replaceable>options</> </optional> <replaceable>dbname</>
         transactions go past their original scheduled end time, it is
         possible for later ones to catch up again.
        </para>
-       <para>        
+       <para>
         When throttling is active, the average and maximum transaction
         schedule lag time are reported in ms.  This is the delay between
         the original scheduled transaction time and the actual transaction

doc/src/sgml/ref/select.sgml

@@ -376,7 +376,7 @@ TABLE [ ONLY ] <replaceable class="parameter">table_name</replaceable> [ * ]
         For example:
 <programlisting>
 SELECT * FROM unnest(ARRAY['a','b','c','d','e','f']) WITH ORDINALITY;
- unnest | ordinality 
+ unnest | ordinality
 --------+----------
  a      |        1
  b      |        2

doc/src/sgml/sources.sgml

@@ -148,7 +148,7 @@ ereport(ERROR,
     function and does not return to the caller. If the severity level is
     lower than <literal>ERROR</>, <function>ereport</> returns normally.
    </para>
-    
+
    <para>
     The available auxiliary routines for <function>ereport</> are:
   <itemizedlist>

doc/src/sgml/syntax.sgml

@@ -1620,7 +1620,7 @@ SELECT
     count(*) AS unfiltered,
     count(*) FILTER (WHERE i < 5) AS filtered
 FROM generate_series(1,10) AS s(i);
- unfiltered | filtered 
+ unfiltered | filtered
 ------------+----------
          10 |        4
 (1 row)