- add util/cformat.sh, which runs clang-format on all C files with
the default .clang-format, and on all header files with a slightly
modified version.
- use correct bracing after multi-line control statements
- stop aligning variable declarations to avoid problems with pointer
alignment, but retain aligned declarations in header files so that
struct definitions look cleaner.
- static function prototypes in C files can skip the line break after
the return type, but function prototypes in header files still have
the line break.
- don't break-before-brace in function definitions. ISC style calls
for braces on the same line when function parameters fit on a single
line, and a line break if they don't, but clang-format doesn't yet
support that distinction. one-line function definitions are about
four times more common than multi-line, so let's use the option that
deviates less.