Adding multithreaded example from issue #3054 (by airween)

- Rewritten to use C++ libModSecurity API and std::thread (instead of
  pthreads)

examples/multithread/Makefile.am

@@ -0,0 +1,54 @@
+
+
+noinst_PROGRAMS = multithread
+
+multithread_SOURCES = \
+	multithread.cc
+
+multithread_LDADD = \
+	$(CURL_LDADD) \
+	$(GEOIP_LDADD) \
+	$(GLOBAL_LDADD) \
+	$(LIBXML2_LDADD) \
+	$(LMDB_LDADD) \
+	$(MAXMIND_LDADD) \
+	$(LUA_LDADD) \
+	$(PCRE_LDADD) \
+	$(SSDEEP_LDADD) \
+	$(YAJL_LDADD)
+
+multithread_LDFLAGS = \
+	-L$(top_builddir)/src/.libs/ \
+	$(GEOIP_LDFLAGS) \
+	-lmodsecurity \
+	-lm \
+	-lstdc++ \
+	$(LMDB_LDFLAGS) \
+	$(LUA_LDFLAGS) \
+	$(MAXMIND_LDFLAGS) \
+	$(SSDEEP_LDFLAGS) \
+	$(YAJL_LDFLAGS)
+
+multithread_CPPFLAGS = \
+	$(GLOBAL_CFLAGS) \
+	-I$(top_builddir)/headers \
+	-I$(top_builddir) \
+	-g \
+	-I../others \
+	-fPIC \
+	-O3 \
+	$(CURL_CFLAGS) \
+	$(GEOIP_CFLAGS) \
+	$(GLOBAL_CPPFLAGS) \
+	$(MODSEC_NO_LOGS) \
+	$(YAJL_CFLAGS) \
+	$(LMDB_CFLAGS) \
+	$(LUA_CFLAGS) \
+	$(PCRE_CFLAGS) \
+	$(LIBXML2_CFLAGS)
+
+
+MAINTAINERCLEANFILES = \
+	Makefile.in
+
+