Change TRUE/FALSE to true/false

The lower case spellings are C and C++ standard and are used in most
parts of the PostgreSQL sources.  The upper case spellings are only used
in some files/modules.  So standardize on the standard spellings.

The APIs for ICU, Perl, and Windows define their own TRUE and FALSE, so
those are left as is when using those APIs.

In code comments, we use the lower-case spelling for the C concepts and
keep the upper-case spelling for the SQL concepts.

Reviewed-by: Michael Paquier <michael.paquier@gmail.com>

src/backend/utils/cache/lsyscache.c

@@ -186,7 +186,7 @@ get_opfamily_member(Oid opfamily, Oid lefttype, Oid righttype,
  *		determine its opfamily, its declared input datatype, and its
  *		strategy number (BTLessStrategyNumber or BTGreaterStrategyNumber).
  *
- * Returns TRUE if successful, FALSE if no matching pg_amop entry exists.
+ * Returns true if successful, false if no matching pg_amop entry exists.
  * (This indicates that the operator is not a valid ordering operator.)
  *
  * Note: the operator could be registered in multiple families, for example
@@ -254,8 +254,8 @@ get_ordering_op_properties(Oid opno,
  *		Get the OID of the datatype-specific btree equality operator
  *		associated with an ordering operator (a "<" or ">" operator).
  *
- * If "reverse" isn't NULL, also set *reverse to FALSE if the operator is "<",
- * TRUE if it's ">"
+ * If "reverse" isn't NULL, also set *reverse to false if the operator is "<",
+ * true if it's ">"
  *
  * Returns InvalidOid if no matching equality operator can be found.
  * (This indicates that the operator is not a valid ordering operator.)
@@ -682,7 +682,7 @@ get_op_btree_interpretation(Oid opno)
 
 /*
  * equality_ops_are_compatible
- *		Return TRUE if the two given equality operators have compatible
+ *		Return true if the two given equality operators have compatible
  *		semantics.
  *
  * This is trivially true if they are the same operator.  Otherwise,
@@ -2868,7 +2868,7 @@ get_attavgwidth(Oid relid, AttrNumber attnum)
  * get_attstatsslot
  *
  *		Extract the contents of a "slot" of a pg_statistic tuple.
- *		Returns TRUE if requested slot type was found, else FALSE.
+ *		Returns true if requested slot type was found, else false.
  *
  * Unlike other routines in this file, this takes a pointer to an
  * already-looked-up tuple in the pg_statistic cache.  We do this since
@@ -2884,7 +2884,7 @@ get_attavgwidth(Oid relid, AttrNumber attnum)
  * reqop: STAOP value wanted, or InvalidOid if don't care.
  * flags: bitmask of ATTSTATSSLOT_VALUES and/or ATTSTATSSLOT_NUMBERS.
  *
- * If a matching slot is found, TRUE is returned, and *sslot is filled thus:
+ * If a matching slot is found, true is returned, and *sslot is filled thus:
  * staop: receives the actual STAOP value.
  * valuetype: receives actual datatype of the elements of stavalues.
  * values: receives pointer to an array of the slot's stavalues.
@@ -2896,7 +2896,7 @@ get_attavgwidth(Oid relid, AttrNumber attnum)
  * wasn't specified.  Likewise, numbers/nnumbers are NULL/0 if
  * ATTSTATSSLOT_NUMBERS wasn't specified.
  *
- * If no matching slot is found, FALSE is returned, and *sslot is zeroed.
+ * If no matching slot is found, false is returned, and *sslot is zeroed.
  *
  * The data referred to by the fields of sslot is locally palloc'd and
  * is independent of the original pg_statistic tuple.  When the caller

src/backend/utils/cache/plancache.c

@@ -319,7 +319,7 @@ CreateOneShotCachedPlan(RawStmt *raw_parse_tree,
  * parserSetup: alternate method for handling query parameters
  * parserSetupArg: data to pass to parserSetup
  * cursor_options: options bitmask to pass to planner
- * fixed_result: TRUE to disallow future changes in query's result tupdesc
+ * fixed_result: true to disallow future changes in query's result tupdesc
  */
 void
 CompleteCachedPlan(CachedPlanSource *plansource,

src/backend/utils/cache/relcache.c

@@ -227,7 +227,7 @@ do { \
 typedef struct opclasscacheent
 {
 	Oid			opclassoid;		/* lookup key: OID of opclass */
-	bool		valid;			/* set TRUE after successful fill-in */
+	bool		valid;			/* set true after successful fill-in */
 	StrategyNumber numSupport;	/* max # of support procs (from pg_am) */
 	Oid			opcfamily;		/* OID of opclass's family */
 	Oid			opcintype;		/* OID of opclass's declared input type */
@@ -5358,9 +5358,9 @@ errtableconstraint(Relation rel, const char *conname)
  * load_relcache_init_file -- attempt to load cache from the shared
  * or local cache init file
  *
- * If successful, return TRUE and set criticalRelcachesBuilt or
+ * If successful, return true and set criticalRelcachesBuilt or
  * criticalSharedRelcachesBuilt to true.
- * If not successful, return FALSE.
+ * If not successful, return false.
  *
  * NOTE: we assume we are already switched into CacheMemoryContext.
  */

src/backend/utils/cache/relmapper.c

@@ -693,13 +693,13 @@ load_relmap_file(bool shared)
  * The magic number and CRC are automatically updated in *newmap.  On
  * success, we copy the data to the appropriate permanent static variable.
  *
- * If write_wal is TRUE then an appropriate WAL message is emitted.
+ * If write_wal is true then an appropriate WAL message is emitted.
  * (It will be false for bootstrap and WAL replay cases.)
  *
- * If send_sinval is TRUE then a SI invalidation message is sent.
+ * If send_sinval is true then a SI invalidation message is sent.
  * (This should be true except in bootstrap case.)
  *
- * If preserve_files is TRUE then the storage manager is warned not to
+ * If preserve_files is true then the storage manager is warned not to
  * delete the files listed in the map.
  *
  * Because this may be called during WAL replay when MyDatabaseId,