Fix typos in Flymake documentation

Fix typos in Flymake documentation

* doc/misc/flymake.texi (Syntax check statuses)
(Adding support for a new syntax check tool)
(Implementation overview, Locating the buildfile): Fix typos.

* lisp/progmodes/flymake-proc.el (flymake-proc--report-fn)
(flymake-proc--find-possible-master-files):Fix typos.
(flymake-proc--panic)
(flymake-proc-legacy-flymake): Fix function reference in doc.

* lisp/progmodes/flymake.el (flymake-error)
(flymake-diagnostic-functions): Fix typos.
(flymake-diagnostic-types-alist): Rephrase and fix typos.
(flymake--backend-state): Fix typos and rephrase.
(flymake--handle-report): Delete empty line.
(flymake--disable-backend)
(flymake--run-backend): Fix typos.
(flymake-goto-next-error, flymake-goto-prev-error): Rephrase.