tasks/translation: delete unreachable BMP request-side branch

http_translate() opened with

    bool TRANSLATE_USE_BMP = false;

as a local variable that was never assigned anywhere else in the tree,
then branched on it:

    if (TRANSLATE_USE_BMP) {
        /* build a BMP blob in memory, base64 it, send */
    } else {
        /* PNG encode via rpng_save_image_bgr24_string */
    }

The if-branch has been unreachable since the variable was introduced.
The else-branch is the one that has actually been running in
production for every translation-service request. Delete the dead
branch, lift the surviving PNG encode out of the pointless else,
localise the 'pitch' temporary into the one block that uses it,
and drop the now-unused 'TRANSLATE_USE_BMP' declaration.

The include of <formats/rbmp.h> was pulled in solely for the
form_bmp_header call inside the dead branch; nothing else in this
file uses the rbmp API (the response-side BMP parsing at line 411
does raw byte-offset reads of the BMP header, not rbmp API calls),
so drop that include too.

Keeps the variable name 'bmp_buffer' / 'bmp64_buffer' / 'bmp64_len'
as-is - they are historical misnomers (the buffer holds PNG bytes,
not BMP) but renaming them is pure churn and would conflict with
other patches in flight.

No behaviour change: only the live branch was reachable before, and
it is what remains.

Note: the response-side PNG path in handle_translation_response has
its own copy-elimination opportunity (a per-pixel strip-alpha loop
that could be folded into the scaler pass), but the scaler does not
currently support ARGB8888 -> RGB565 as either a direct pixconv or
via the full-pipeline path (see libretro-common/gfx/scaler/scaler.c
lines 150-167 and 239-263), so replacing the intermediate BGR24
buffer would break the RGB565-core code path. That refactor needs
either a new conv_argb8888_rgb565 entry in the scaler or a two-pass
approach and is deferred to a separate commit.

Author: LibretroAdmin

tasks/task_translation.c

@@ -26,7 +26,6 @@
 #endif
 
 #include <encodings/base64.h>
-#include <formats/rbmp.h>
 #include <formats/rpng.h>
 #include <formats/rjson.h>
 #include <gfx/scaler/pixconv.h>
@@ -1200,14 +1199,12 @@ static bool http_translate(
       void *userdata)
 {
    uint8_t *bmp_buffer               = NULL;
-   size_t pitch;
    uint64_t buffer_bytes             = 0;
    char *bmp64_buffer                = NULL;
    rjsonwriter_t *jsonwriter         = NULL;
    const char *json_buffer           = NULL;
    http_translate_ctx_t *ctx         = NULL;
    int bmp64_len                     = 0;
-   bool TRANSLATE_USE_BMP            = false;
    bool success                      = false;
    settings_t *settings              = config_get_ptr();
    video_driver_state_t *video_st    = video_state_get_ptr();
@@ -1218,28 +1215,17 @@ static bool http_translate(
    access_state_t *access_st         = access_state_get_ptr();
 #endif
 
-   if (TRANSLATE_USE_BMP)
-   {
-      /*
-        At this point, we should have a screenshot in the buffer,
-        so allocate an array to contain the BMP image along with
-        the BMP header as bytes, and then covert that to a
-        b64 encoded array for transport in JSON.
-      */
-      if (!(bmp_buffer  = (uint8_t*)malloc(width * height * 3 + 54)))
-         goto finish;
-
-      form_bmp_header(bmp_buffer, width, height, false);
-      memcpy(bmp_buffer + 54,
-            bit24_image,
-            width * height * 3 * sizeof(uint8_t));
-      buffer_bytes = sizeof(uint8_t) * (width * height * 3 + 54);
-   }
-   else
+   /* Encode the framebuffer screenshot as a PNG (BGR24) for the
+    * translation service.  rpng_save_image_bgr24_string handles the
+    * vertical flip via negative stride + bottom-row pointer, so no
+    * intermediate buffer is needed.  Variable is named bmp_buffer for
+    * historical reasons (the request format was originally a BMP
+    * blob gated on an always-false TRANSLATE_USE_BMP local; that
+    * branch has been deleted as dead code). */
    {
-      pitch        = width * 3;
+      size_t pitch = width * 3;
       bmp_buffer   = rpng_save_image_bgr24_string(
-            bit24_image + width * (height-1) * 3,
+            bit24_image + width * (height - 1) * 3,
             width, height, (signed)-pitch, &buffer_bytes);
    }