pgrowlocks: change lock mode output labels for consistency

Change "Share" to "For Share" and "Key Share" to "For Key Share" for
consistency with other lock mode labels.

BACKWARD COMPATIBILITY BREAK

Reported-by: David Cook

Discussion:  https://postgr.es/m/CA+dNBPNBf+FCEwohe7SH1tSks0R_G4F=tuvM=hnPs4qWiAH8vg@mail.gmail.com

Backpatch-through: master

contrib/pgrowlocks/expected/pgrowlocks.out

@@ -136,10 +136,10 @@ a|b
 (2 rows)
 
 step s2_rowlocks: SELECT locked_row, multi, modes FROM pgrowlocks('multixact_conflict');
-locked_row|multi|modes              
-----------+-----+-------------------
-(0,1)     |t    |{"Key Share",Share}
-(0,2)     |t    |{"Key Share",Share}
+locked_row|multi|modes                        
+----------+-----+-----------------------------
+(0,1)     |t    |{"For Key Share","For Share"}
+(0,2)     |t    |{"For Key Share","For Share"}
 (2 rows)
 
 step s1_commit: COMMIT;
@@ -161,10 +161,10 @@ a|b
 (2 rows)
 
 step s2_rowlocks: SELECT locked_row, multi, modes FROM pgrowlocks('multixact_conflict');
-locked_row|multi|modes                            
-----------+-----+---------------------------------
-(0,1)     |t    |{"Key Share","For No Key Update"}
-(0,2)     |t    |{"Key Share","For No Key Update"}
+locked_row|multi|modes                                
+----------+-----+-------------------------------------
+(0,1)     |t    |{"For Key Share","For No Key Update"}
+(0,2)     |t    |{"For Key Share","For No Key Update"}
 (2 rows)
 
 step s1_commit: COMMIT;
@@ -186,10 +186,10 @@ a|b
 (2 rows)
 
 step s2_rowlocks: SELECT locked_row, multi, modes FROM pgrowlocks('multixact_conflict');
-locked_row|multi|modes                     
-----------+-----+--------------------------
-(0,1)     |t    |{"Key Share","For Update"}
-(0,2)     |t    |{"Key Share","For Update"}
+locked_row|multi|modes                         
+----------+-----+------------------------------
+(0,1)     |t    |{"For Key Share","For Update"}
+(0,2)     |t    |{"For Key Share","For Update"}
 (2 rows)
 
 step s1_commit: COMMIT;
@@ -205,10 +205,10 @@ a|b
 
 step s1_updatea: UPDATE multixact_conflict SET a = 10 WHERE a = 1;
 step s2_rowlocks: SELECT locked_row, multi, modes FROM pgrowlocks('multixact_conflict');
-locked_row|multi|modes               
-----------+-----+--------------------
-(0,1)     |t    |{"Key Share",Update}
-(0,2)     |f    |{"For Key Share"}   
+locked_row|multi|modes                   
+----------+-----+------------------------
+(0,1)     |t    |{"For Key Share",Update}
+(0,2)     |f    |{"For Key Share"}       
 (2 rows)
 
 step s1_commit: COMMIT;
@@ -224,10 +224,10 @@ a|b
 
 step s1_updateb: UPDATE multixact_conflict SET b = 11 WHERE b = 4;
 step s2_rowlocks: SELECT locked_row, multi, modes FROM pgrowlocks('multixact_conflict');
-locked_row|multi|modes                        
-----------+-----+-----------------------------
-(0,1)     |f    |{"For Key Share"}            
-(0,2)     |t    |{"Key Share","No Key Update"}
+locked_row|multi|modes                            
+----------+-----+---------------------------------
+(0,1)     |f    |{"For Key Share"}                
+(0,2)     |t    |{"For Key Share","No Key Update"}
 (2 rows)
 
 step s1_commit: COMMIT;

contrib/pgrowlocks/pgrowlocks.c

@@ -200,10 +200,10 @@ pgrowlocks(PG_FUNCTION_ARGS)
 								snprintf(buf, NCHARS, "For No Key Update");
 								break;
 							case MultiXactStatusForShare:
-								snprintf(buf, NCHARS, "Share");
+								snprintf(buf, NCHARS, "For Share");
 								break;
 							case MultiXactStatusForKeyShare:
-								snprintf(buf, NCHARS, "Key Share");
+								snprintf(buf, NCHARS, "For Key Share");
 								break;
 						}
 						strcat(values[Atnum_modes], buf);

doc/src/sgml/pgrowlocks.sgml

@@ -74,7 +74,7 @@ pgrowlocks(text) returns setof record
       <entry><structfield>modes</structfield></entry>
       <entry><type>text[]</type></entry>
       <entry>Lock mode of lockers (more than one if multitransaction),
-       an array of <literal>Key Share</literal>, <literal>Share</literal>,
+       an array of <literal>For Key Share</literal>, <literal>For Share</literal>,
        <literal>For No Key Update</literal>, <literal>No Key Update</literal>,
        <literal>For Update</literal>, <literal>Update</literal>.</entry>
      </row>