Simplify avifROStreamReadBoxHeader() slightly

Use an equivalent function call that's slightly shorter.

src/stream.c

diff --git a/src/stream.c b/src/stream.c
index 56965a8..2c4e822 100644
--- a/src/stream.c
+++ b/src/stream.c
@@ -297,7 +297,7 @@
 avifBool avifROStreamReadBoxHeader(avifROStream * stream, avifBoxHeader * header)
 {
     AVIF_CHECK(avifROStreamReadBoxHeaderPartial(stream, header, /*topLevel=*/AVIF_FALSE));
-    if (header->size > avifROStreamRemainingBytes(stream)) {
+    if (!avifROStreamHasBytesLeft(stream, header->size)) {
         avifDiagnosticsPrintf(stream->diag, "%s: Child box too large, possibly truncated data", stream->diagContext);
         return AVIF_FALSE;
     }