ox-latex: Erase compile buffer at the start

* lisp/ox-latex.el (org-latex-compile): Before running the compile
command, erase the log buffer to ensure that stale/old logging is
cleared.

lisp/ox-latex.el

@@ -4301,6 +4301,8 @@ produced."
          (outfile (org-compile-file texfile process "pdf"
 				    (format "See %S for details" log-buf-name)
 				    log-buf spec)))
+    (with-current-buffer log-buf
+      (erase-buffer))
     (org-latex-compile--postprocess outfile log-buf snippet)
     ;; Return output file name.
     outfile))