Add build/ dir for alterl bindings and remove them from .gitignore

Summary: These files are copied from the erl/build dir. I don't know why
         I accidentally gitignored them before.


git-svn-id: https://svn.apache.org/repos/asf/incubator/thrift/trunk@666413 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/lib/alterl/build/buildtargets.mk b/lib/alterl/build/buildtargets.mk
new file mode 100644
index 0000000..db52b78
--- /dev/null
+++ b/lib/alterl/build/buildtargets.mk
@@ -0,0 +1,15 @@
+EBIN ?= ../ebin
+ESRC ?= .
+EMULATOR = beam
+
+ERLC_WFLAGS = -W
+ERLC = erlc $(ERLC_WFLAGS) $(ERLC_FLAGS)
+ERL = erl -boot start_clean
+
+$(EBIN)/%.beam: $(ESRC)/%.erl
+	@echo "   ERLC  $<"
+	@$(ERLC) $(ERL_FLAGS) $(ERL_COMPILE_FLAGS) -o$(EBIN) $<
+
+.erl.beam:
+	$(ERLC) $(ERL_FLAGS) $(ERL_COMPILE_FLAGS) -o$(dir $@) $<
+