export backends: Fix "PDF file ... wasn't produced" error with relative paths

* lisp/ox-latex.el (org-latex-compile): Make sure generated file can
  be found by `file-exists-p'.
* contrib/lisp/ox-groff.el (org-groff-compile): Make sure generated
  file can be found by `file-exists-p'.
* lisp/ox-man.el (org-man-compile): Make sure generated file can be
  found by `file-exists-p'.
* lisp/ox-texinfo.el (org-texinfo-compile): Make sure generated file
  can be found by `file-exists-p'.

contrib/lisp/ox-groff.el

@@ -1949,7 +1949,7 @@ Return PDF file name or an error if it couldn't be produced."
 	  ;; Collect standard errors from output buffer.
 	  (setq errors (org-groff-collect-errors outbuf))))
        (t (error "No valid command to process to PDF")))
-      (let ((pdffile (concat out-dir base-name ".pdf")))
+      (let ((pdffile (concat (file-name-sans-extension full-name) ".pdf")))
 	;; Check for process failure.  Provide collected errors if
 	;; possible.
 	(if (not (file-exists-p pdffile))

lisp/ox-latex.el

@@ -2892,7 +2892,7 @@ Return PDF file name or an error if it couldn't be produced."
 	  ;; Collect standard errors from output buffer.
 	  (setq errors (and (not snippet) (org-latex--collect-errors outbuf)))))
        (t (error "No valid command to process to PDF")))
-      (let ((pdffile (concat out-dir base-name ".pdf")))
+      (let ((pdffile (concat (file-name-sans-extension full-name) ".pdf")))
 	;; Check for process failure.  Provide collected errors if
 	;; possible.
 	(if (not (file-exists-p pdffile))

lisp/ox-man.el

@@ -1233,7 +1233,7 @@ Return PDF file name or an error if it couldn't be produced."
 	  ;; Collect standard errors from output buffer.
 	  (setq errors (org-man-collect-errors outbuf))))
        (t (error "No valid command to process to PDF")))
-      (let ((pdffile (concat out-dir base-name ".pdf")))
+      (let ((pdffile (concat (file-name-sans-extension full-name) ".pdf")))
 	;; Check for process failure.  Provide collected errors if
 	;; possible.
 	(if (not (file-exists-p pdffile))

lisp/ox-texinfo.el

@@ -1827,7 +1827,7 @@ Return INFO file name or an error if it couldn't be produced."
 	  ;; Collect standard errors from output buffer.
 	  (setq errors (org-texinfo-collect-errors outbuf))))
        (t (error "No valid command to process to Info")))
-      (let ((infofile (concat out-dir base-name ".info")))
+      (let ((infofile (concat (file-name-sans-extension full-name) ".info")))
 	;; Check for process failure.  Provide collected errors if
 	;; possible.
 	(if (not (file-exists-p infofile))