Most instances of ;; in C code are mistakes, where the second
semicolon is a no-op. This rule tries to make it easy to flag
the typos occuring at the end of a statement. It intentionally
does not flag for(;;) loops, and misses grammar problems in
comments if the problem occurs in the middle of the line.
Shell files (including configure.ac and Makefile.am, which can
contain shell snippets) are too likely to use case statements
where ;; is legitimate, so those are not scanned.
* top/maint.mk (sc_prohibit_double_semicolon): New rule.
Signed-off-by: Eric Blake <email@example.com>