checkpatch: ignore existing CamelCase uses from include/...

checkpatch: ignore existing CamelCase uses from include/...

When using --strict, CamelCase uses are described with CHECK: messages.
These CamelCase uses may be acceptable and should not generate these
messages when the variable is already defined in a file from the
include/...  path.

So, change checkpatch to read all the .h files in include/...  and look
for preexisting CamelCase #defines, typedefs and function prototypes.

Add these to the existing camelcase hash so that any uses in the patch or
file can be ignored.

There are currently ~3500 files in include/.  It takes about 10 cpu
seconds on my little netbook to grep for and preseed these existing uses.

That's about 4x the time for a similar git grep.

This preseeding is only done once when using --strict and only when there
is a CamelCase use found.

If a .git directory is found, it uses 'git ls-files include' If not, it
uses 'find $root/include -name "*.h"

Signed-off-by: Joe Perches <joe@perches.com>
Cc: Andy Whitcroft <apw@canonical.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>