[PATCH BlueZ] build: Fix build with latest tree

From: Luiz Augusto von Dentz <redacted>

Latest ell tree has introduced useful.h and main-private.h which are
required to build:

ell/cert-crypto.c:35:10: fatal error: useful.h: No such file or
directory
   35 | #include "useful.h"
         |          ^~~~~~~~~~
...
---
 Makefile.am | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/Makefile.am b/Makefile.am
index ff0df2196..7fce2e7c0 100644
--- a/Makefile.am
+++ b/Makefile.am

@@ -135,7 +135,9 @@ ell_headers = ell/util.h \
 			ell/asn1-private.h \
 			ell/cert-private.h \
 			ell/pem-private.h \
-			ell/uuid.h
+			ell/uuid.h \
+			ell/useful.h \
+			ell/main-private.h
 
 ell_sources = ell/private.h ell/missing.h \
 			ell/util.c \

-- 
2.30.2