merge: Tidy the code - Part 2

 * build: force OPS to be rebuild after a reconfigure
 * build: fix minor code warnings / style
 * tidy: be specific about void functions
 * build: expand a few more alloc macros
 * tidy: add argument names to function prototypes
 * build: drop local copy of regex code
 * tidy: indent the docbook manual
 * tidy: rearrange code to avoid forward declarations
 * tidy: limit the scope of some functions
 * build: give the compress functions a unique name
 * tidy: use snake_case for function names
 * build: add missing newlines to mutt_debug