Correct some custom type typos

* lisp/image.el (image-use-external-converter):
* lisp/progmodes/sql.el (sql-use-indent-support):
* lisp/vc/add-log.el (add-log-dont-create-changelog-file): Fix
misspelled 'boolean custom type.

* lisp/progmodes/flymake-cc.el (flymake-cc-command): Correct custom
type specification.  (Bug#30990)

lisp/image.el

@@ -148,7 +148,7 @@ and some others) internally, but images that don't have native
 support in Emacs can still be displayed if an external conversion
 program (like ImageMagick \"convert\", GraphicsMagick \"gm\"
 or \"ffmpeg\") is installed."
-  :type 'bool
+  :type 'boolean
   :version "27.1")
 
 ;; Map put into text properties on images.

lisp/progmodes/flymake-cc.el

@@ -37,7 +37,8 @@ syntax of a (Obj)C(++) program passed to it via its standard
 input and prints the result on its standard output."
   :type '(choice
           (symbol :tag "Function")
-          ((repeat :) string))
+          (repeat :tag "Command(s)" string))
+  :version "27.1"
   :group 'flymake-cc)
 
 (defun flymake-cc--make-diagnostics (source)

lisp/progmodes/sql.el

@@ -737,7 +737,7 @@ requirements.
 The package must be available to be loaded and activated."
   :group 'SQL
   :link '(url-link "https://elpa.gnu.org/packages/sql-indent.html")
-  :type 'booleanp
+  :type 'boolean
   :version "27.1")
 
 (defun sql-indent-enable ()

lisp/vc/add-log.el

@@ -811,7 +811,7 @@ Optional arg BUFFER-FILE overrides `buffer-file-name'."
   "If non-nil, don't create ChangeLog files for log entries.
 If a ChangeLog file does not already exist, a non-nil value
 means to put log entries in a suitably named buffer."
-  :type :boolean
+  :type 'boolean
   :version "27.1")
 
 (put 'add-log-dont-create-changelog-file 'safe-local-variable 'booleanp)