ox-latex: Use lexical binding

ox-latex: Use lexical binding

* lisp/ox-latex.el (org-latex-format-drawer-function):
(org-latex-bold):
(org-latex-clock):
(org-latex-code):
(org-latex-entity):
(org-latex-example-block):
(org-latex-export-block):
(org-latex-export-snippet):
(org-latex-fixed-width):
(org-latex-footnote-reference):
(org-latex-format-headline-default-function):
(org-latex-horizontal-rule):
(org-latex-inline-src-block):
(org-latex-format-inlinetask-default-function):
(org-latex-italic):
(org-latex-keyword):
(org-latex-latex-environment):
(org-latex-latex-fragment):
(org-latex-line-break):
(org-latex-node-property):
(org-latex-paragraph):
(org-latex-planning):
(org-latex-property-drawer):
(org-latex-matrices):
(org-latex-matrices-tree-filter):
(org-latex-math-block-tree-filter):
(org-latex-math-block-options-filter):
(org-latex-math-block):
(org-latex-section):
(org-latex-src-block):
(org-latex-statistics-cookie):
(org-latex-strike-through):
(org-latex--script-size):
(org-latex-subscript):
(org-latex-superscript):
(org-latex-target):
(org-latex-timestamp):
(org-latex-underline):
(org-latex-verbatim):
(org-latex-compile): Silence byte-compiler.  Refactor `mapc' + `lambda'
into `dolist'.