build: Add check for required Crypto++ library

Change-Id: I3e4db0e3b3d2c00f0a66dda0c69c4325b836b75e
diff --git a/Makefile.am b/Makefile.am
index 4533a01..850d034 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -120,8 +120,8 @@
   src/util/string-helper.hpp \
   src/util/time.hpp
 
-libndn_cpp_la_LIBADD  = @OPENSSL_LIBS@ @OSX_SECURITY_LIBS@
-libndn_cpp_la_LDFLAGS = @OPENSSL_LDFLAGS@  @SQLITE3_LDFLAGS@ @BOOST_LDFLAGS@
-libndn_cpp_la_CFLAGS  = @OPENSSL_INCLUDES@ @SQLITE3_CFLAGS@  @BOOST_CPPFLAGS@
+libndn_cpp_la_LIBADD  = @OPENSSL_LIBS@ @CRYPTOPP_LIBS@ @OSX_SECURITY_LIBS@
+libndn_cpp_la_LDFLAGS = @OPENSSL_LDFLAGS@  @CRYPTOPP_LDFLAGS@ @SQLITE3_LDFLAGS@ @BOOST_LDFLAGS@
+libndn_cpp_la_CFLAGS  = @OPENSSL_INCLUDES@ @CRYPTOPP_INCLUDES@ @SQLITE3_CFLAGS@  @BOOST_CPPFLAGS@
 
 dist_noinst_SCRIPTS = autogen.sh