build: Fix build with latest ELL tree

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"
         |          ^~~~~~~~~~
...

Signed-off-by: Anuj Jain <anuj01.jain@samsung.com>
Signed-off-by: Ayush Garg <ayush.garg@samsung.com>

diff --git a/Makefile.am b/Makefile.am
index efe2891..35822ab 100755 (executable)
--- a/Makefile.am
+++ b/Makefile.am
@@ -136,7 +136,10 @@ ell_headers = ell/util.h \
                         ell/asn1-private.h \
                         ell/cert-private.h \
                         ell/pem-private.h \
-                       ell/uuid.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 \