build: Add and build OpenFST submodule.

.gitmodules

@@ -55,3 +55,6 @@
 [submodule "glslang"]
 	path = glslang
 	url = https://github.com/KhronosGroup/glslang
+[submodule "openfst"]
+	path = openfst
+	url = https://github.com/alphacep/openfst

Makefile.in

@@ -381,6 +381,46 @@ $(OBJ)/.steamexe-post-build64:
 	cp $(SRC)/steam_helper/64/libsteam_api.so $(DST_LIBDIR64)/
 	touch $@
 
+##
+## openfst
+##
+
+OPENFST_SOURCE_ARGS = \
+  --include src/include/fst/config.h.in \
+  --exclude aclocal.m4 \
+  --exclude ar-lib \
+  --exclude autom4te.cache \
+  --exclude compile \
+  --exclude config.guess \
+  --exclude config.h.in \
+  --exclude config.sub \
+  --exclude configure \
+  --exclude depcomp \
+  --exclude install-sh \
+  --exclude ltmain.sh \
+  --exclude m4/libtool.m4 \
+  --exclude m4/ltoptions.m4 \
+  --exclude m4/ltsugar.m4 \
+  --exclude m4/ltversion.m4 \
+  --exclude m4/lt~obsolete.m4 \
+  --exclude Makefile.in \
+  --exclude missing \
+  --exclude test-driver \
+
+OPENFST_CONFIGURE_ARGS = \
+  --enable-silent-rules \
+  --enable-static \
+  --disable-shared \
+  --enable-far \
+  --enable-ngram-fsts \
+  --enable-lookahead-fsts \
+  --with-pic \
+  --disable-bin \
+
+$(eval $(call rules-source,openfst,$(SRCDIR)/openfst))
+$(eval $(call rules-autoconf,openfst,32))
+$(eval $(call rules-autoconf,openfst,64))
+
 
 ##
 ## wine

openfst

@@ -0,0 +1 @@
+Subproject commit 7dfd808194105162f20084bb4d8e4ee4b65266d5