Merge branch 'ab/attribute-format'

Many "printf"-like helper functions we have have been annotated
with __attribute__() to catch placeholder/parameter mismatches.

* ab/attribute-format:
  advice.h: add missing __attribute__((format)) & fix usage
  *.h: add a few missing __attribute__((format))
  *.c static functions: add missing __attribute__((format))
  sequencer.c: move static function to avoid forward decl
  *.c static functions: don't forward-declare __attribute__

midx.c

@@ -1172,6 +1172,7 @@ void clear_midx_file(struct repository *r)
 
 static int verify_midx_error;
 
+__attribute__((format (printf, 1, 2)))
 static void midx_report(const char *fmt, ...)
 {
 	va_list ap;