Rename SnapBuild* macros in slot.c.

Same macro names for SnapBuildOnDiskNotChecksummedSize and
SnapBuildOnDiskChecksummedSize are being used in slot.c and snapbuild.c.
This patch renames them, in slot.c, to
ReplicationSlotOnDiskNotChecksummedSize and
ReplicationSlotOnDiskChecksummedSize similar to the other macros. This
makes all macro names look consistent in slot.c.

Author: Bharath Rupireddy
Discussion: https://postgr.es/m/CALj2ACVZo-piDGzBOJRY4ob=_goFR6t9DhZMDMjJWN7LQs34Aw@mail.gmail.com

Author: Amit Kapila

src/backend/replication/slot.c

@@ -77,11 +77,11 @@ typedef struct ReplicationSlotOnDisk
 #define ReplicationSlotOnDiskConstantSize \
 	offsetof(ReplicationSlotOnDisk, slotdata)
 /* size of the part of the slot not covered by the checksum */
-#define SnapBuildOnDiskNotChecksummedSize \
+#define ReplicationSlotOnDiskNotChecksummedSize  \
 	offsetof(ReplicationSlotOnDisk, version)
 /* size of the part covered by the checksum */
-#define SnapBuildOnDiskChecksummedSize \
-	sizeof(ReplicationSlotOnDisk) - SnapBuildOnDiskNotChecksummedSize
+#define ReplicationSlotOnDiskChecksummedSize \
+	sizeof(ReplicationSlotOnDisk) - ReplicationSlotOnDiskNotChecksummedSize
 /* size of the slot data that is version dependent */
 #define ReplicationSlotOnDiskV2Size \
 	sizeof(ReplicationSlotOnDisk) - ReplicationSlotOnDiskConstantSize
@@ -1571,8 +1571,8 @@ SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel)
 	SpinLockRelease(&slot->mutex);
 
 	COMP_CRC32C(cp.checksum,
-				(char *) (&cp) + SnapBuildOnDiskNotChecksummedSize,
-				SnapBuildOnDiskChecksummedSize);
+				(char *) (&cp) + ReplicationSlotOnDiskNotChecksummedSize,
+				ReplicationSlotOnDiskChecksummedSize);
 	FIN_CRC32C(cp.checksum);
 
 	errno = 0;
@@ -1787,8 +1787,8 @@ RestoreSlotFromDisk(const char *name)
 	/* now verify the CRC */
 	INIT_CRC32C(checksum);
 	COMP_CRC32C(checksum,
-				(char *) &cp + SnapBuildOnDiskNotChecksummedSize,
-				SnapBuildOnDiskChecksummedSize);
+				(char *) &cp + ReplicationSlotOnDiskNotChecksummedSize,
+				ReplicationSlotOnDiskChecksummedSize);
 	FIN_CRC32C(checksum);
 
 	if (!EQ_CRC32C(checksum, cp.checksum))