Fix mongoose/examples compilation with mingw

    PUBLISHED_FROM=46800f43ba03082cc589d70e6118d754f4cdc9d0

examples/websocket_chat/Makefile

-# Copyright (c) 2014 Cesanta Software
-# All rights reserved
-
 PROG = websocket_chat
-CFLAGS = -W -Wall -I../.. -pthread -g -O0 $(CFLAGS_EXTRA)
-SOURCES = $(PROG).c ../../mongoose.c
-
-$(PROG): $(SOURCES)
-	$(CC) -o $(PROG) $(SOURCES) $(CFLAGS)
-
-clean:
-	rm -rf $(PROG) *.exe *.dSYM *.obj *.exp .*o *.lib
+include ../examples.mk