fix compiler warnings

* lisp/ob.el (org-strip-protective-commas): Declared.
* lisp/org-agenda.el (org-agenda-filtered-by-category): Declared.
  (org-agenda-filter-apply): Capture free variable.
* lisp/org-footnote.el (org-skip-whitespace): Declared.
* lisp/org-mobile.el (org-agenda-filter): Declared.
* lisp/org-src.el (org-strip-protective-commas): Declared.

lisp/ob.el

@@ -57,6 +57,7 @@
 (declare-function org-cycle "org" (&optional arg))
 (declare-function org-uniquify "org" (list))
 (declare-function org-current-level "org" ())
+(declare-function org-strip-protective-commas "org" (beg end))
 (declare-function org-table-import "org-table" (file arg))
 (declare-function org-add-hook "org-compat"
 		  (hook function &optional append local))

lisp/org-agenda.el

@@ -6191,7 +6191,7 @@ When this is the global TODO list, a prefix argument will be interpreted."
 
 (defvar org-global-tags-completion-table nil)
 (defvar org-agenda-filter-form nil)
-
+(defvar org-agenda-filtered-by-category nil)
 (defun org-agenda-filter-by-category (strip)
   "Keep only those lines in the agenda buffer that have a specific category.
 The category is that of the current line."
@@ -6369,10 +6369,9 @@ If the line does not have an effort defined, return nil."
       (funcall op (or eff (if org-sort-agenda-noeffort-is-high 32767 0))
 	       value))))
 
-(defvar org-agenda-filtered-by-category nil)
 (defun org-agenda-filter-apply (filter type)
   "Set FILTER as the new agenda filter and apply it."
-  (let (tags)
+  (let (tags cat)
     (if (eq type 'tag)
 	(setq org-agenda-tag-filter filter)
       (setq org-agenda-category-filter filter

lisp/org-footnote.el

@@ -57,6 +57,7 @@
 (declare-function org-mark-ring-push "org" (&optional pos buffer))
 (declare-function org-show-context "org" (&optional key))
 (declare-function org-trim "org" (s))
+(declare-function org-skip-whitespace "org" ())
 (declare-function outline-next-heading "outline")
 
 (defvar org-outline-regexp-bol)		; defined in org.el

lisp/org-mobile.el

@@ -295,6 +295,8 @@ Also exclude files matching `org-mobile-files-exclude-regexp'."
 	(push (cons file link-name) rtn)))
     (nreverse rtn)))
 
+(defvar org-agenda-filter)
+
 ;;;###autoload
 (defun org-mobile-push ()
   "Push the current state of Org affairs to the WebDAV directory.

lisp/org-src.el

@@ -41,6 +41,7 @@
 (declare-function org-at-table.el-p "org" ())
 (declare-function org-get-indentation "org" (&optional line))
 (declare-function org-switch-to-buffer-other-window "org" (&rest args))
+(declare-function org-strip-protective-commas "org" (beg end))
 (declare-function org-pop-to-buffer-same-window 
 		  "org-compat" (&optional buffer-or-name norecord label))