checkpatch: add a --strict test for structs with bool member definitions

A struct with a bool member can have different sizes on various
architectures because neither bool size nor alignment is standardized.

So emit a message on the use of bool in structs only in .h files and not
.c files.

There is the real possibility that this test could have a false positive
when a bool is declared as an automatic, so limit the test to .h files
where the only false positive is for declarations in static inline
functions.

Link: http://lkml.kernel.org/r/95477c93db187bab6da8a8ba7c57836868446179.camel@perches.com
Signed-off-by: Joe Perches <joe@perches.com>
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

scripts/checkpatch.pl

@@ -6251,6 +6251,13 @@ sub process {
 			     "Avoid using bool as bitfield.  Prefer bool bitfields as unsigned int or u<8|16|32>\n" . $herecurr);
 		}
 
+# check for bool use in .h files
+		if ($realfile =~ /\.h$/ &&
+		    $sline =~ /^.\s+bool\s*$Ident\s*(?::\s*d+\s*)?;/) {
+			CHK("BOOL_MEMBER",
+			    "Avoid using bool structure members because of possible alignment issues - see: https://lkml.org/lkml/2017/11/21/384\n" . $herecurr);
+		}
+
 # check for semaphores initialized locked
 		if ($line =~ /^.\s*sema_init.+,\W?0\W?\)/) {
 			WARN("CONSIDER_COMPLETION",