Make verify_compact_attribute available in non-assert builds

6f3820f adjusted the assert-enabled validation of the CompactAttribute
to call a new external function to perform the validation.  That commit
made it so the function was only available when building with
USE_ASSERT_CHECKING, and because TupleDescCompactAttr() is a static
inline function, the call to verify_compact_attribute() was compiled
into any extension which uses TupleDescCompactAttr().  This caused issues
for such extensions when loading the assert-enabled extension into
PostgreSQL versions without asserts enabled due to that function being
unavailable in core.

To fix this, make verify_compact_attribute() available unconditionally,
but make it do nothing unless building with USE_ASSERT_CHECKING.

Author: Andrew Kane <andrew@ankane.org>
Reviewed-by: David Rowley <dgrowleyml@gmail.com>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/CAOdR5yHfMEMW00XGo=v1zCVUS6Huq2UehXdvKnwtXPTcZwXhmg@mail.gmail.com

Author: david-rowley

src/backend/access/common/tupdesc.c

@@ -118,7 +118,6 @@ populate_compact_attribute(TupleDesc tupdesc, int attnum)
 	populate_compact_attribute_internal(src, dst);
 }
 
-#ifdef USE_ASSERT_CHECKING
 /*
  * verify_compact_attribute
  *		In Assert enabled builds, we verify that the CompactAttribute is
@@ -132,6 +131,7 @@ populate_compact_attribute(TupleDesc tupdesc, int attnum)
 void
 verify_compact_attribute(TupleDesc tupdesc, int attnum)
 {
+#ifdef USE_ASSERT_CHECKING
 	CompactAttribute *cattr = &tupdesc->compact_attrs[attnum];
 	Form_pg_attribute attr = TupleDescAttr(tupdesc, attnum);
 	CompactAttribute tmp;
@@ -150,9 +150,8 @@ verify_compact_attribute(TupleDesc tupdesc, int attnum)
 
 	/* Check the freshly populated CompactAttribute matches the TupleDesc's */
 	Assert(memcmp(&tmp, cattr, sizeof(CompactAttribute)) == 0);
-}
 #endif
-
+}
 
 /*
  * CreateTemplateTupleDesc

src/include/access/tupdesc.h

@@ -158,9 +158,7 @@ TupleDescAttr(TupleDesc tupdesc, int i)
 
 #undef TupleDescAttrAddress
 
-#ifdef USE_ASSERT_CHECKING
 extern void verify_compact_attribute(TupleDesc, int attnum);
-#endif
 
 /*
  * Accessor for the i'th CompactAttribute element of tupdesc.