[chore] tidy up media manager, add calling func to errors, build-script improvements (#1835)

* media manager tidy-up: de-interface and remove unused PostDataFunc

Signed-off-by: kim <grufwub@gmail.com>

* remove last traces of media.Manager being an interface

Signed-off-by: kim <grufwub@gmail.com>

* update error to provide caller, allow tuneable via build tags

Signed-off-by: kim <grufwub@gmail.com>

* remove kim-specific build script changes

Signed-off-by: kim <grufwub@gmail.com>

* fix merge conflicts

Signed-off-by: kim <grufwub@gmail.com>

* update build-script to support externally setting build variables

Signed-off-by: kim <grufwub@gmail.com>

---------

Signed-off-by: kim <grufwub@gmail.com>

internal/media/processingmedia.go

@@ -40,12 +40,11 @@ import (
 type ProcessingMedia struct {
 	media   *gtsmodel.MediaAttachment // processing media attachment details
 	dataFn  DataFunc                  // load-data function, returns media stream
-	postFn  PostDataCallbackFunc      // post data callback function
 	recache bool                      // recaching existing (uncached) media
 	done    bool                      // done is set when process finishes with non ctx canceled type error
 	proc    runners.Processor         // proc helps synchronize only a singular running processing instance
 	err     error                     // error stores permanent error value when done
-	mgr     *manager                  // mgr instance (access to db / storage)
+	mgr     *Manager                  // mgr instance (access to db / storage)
 }
 
 // AttachmentID returns the ID of the underlying media attachment without blocking processing.
@@ -143,17 +142,6 @@ func (p *ProcessingMedia) load(ctx context.Context) (*gtsmodel.MediaAttachment,
 // and updates the underlying attachment fields as necessary. It will then stream
 // bytes from p's reader directly into storage so that it can be retrieved later.
 func (p *ProcessingMedia) store(ctx context.Context) error {
-	defer func() {
-		if p.postFn == nil {
-			return
-		}
-
-		// ensure post callback gets called.
-		if err := p.postFn(ctx); err != nil {
-			log.Errorf(ctx, "error executing postdata function: %v", err)
-		}
-	}()
-
 	// Load media from provided data fun
 	rc, sz, err := p.dataFn(ctx)
 	if err != nil {