handle USE_AESNI for mingw

Makefile.mingw

@@ -2,6 +2,10 @@ CXX = g++
 CXXFLAGS = -O2 -D_MT -DWIN32 -D_WINDOWS -DWIN32_LEAN_AND_MEAN
 NEEDED_CXXFLAGS = -std=c++11
 BOOST_SUFFIX = -mt
-INCFLAGS = -I/usr/include/ -I/usr/local/include/ -I/c/dev/openssl/include -I/c/dev/boost/include/boost-1_59 
+INCFLAGS = -I/usr/include/ -I/usr/local/include/
 LDFLAGS = -Wl,-rpath,/usr/local/lib -L/usr/local/lib -L/c/dev/openssl -L/c/dev/boost/lib
 LDLIBS = -Wl,-Bstatic -lboost_system$(BOOST_SUFFIX) -Wl,-Bstatic -lboost_date_time$(BOOST_SUFFIX) -Wl,-Bstatic -lboost_filesystem$(BOOST_SUFFIX) -Wl,-Bstatic -lboost_regex$(BOOST_SUFFIX) -Wl,-Bstatic -lboost_program_options$(BOOST_SUFFIX) -Wl,-Bstatic -lssl -Wl,-Bstatic -lcrypto -Wl,-Bstatic -lz -Wl,-Bstatic -lwsock32 -Wl,-Bstatic -lws2_32 -Wl,-Bstatic -lgdi32 -Wl,-Bstatic -liphlpapi -static-libgcc -static-libstdc++ -Wl,-Bstatic -lstdc++ -Wl,-Bstatic -lpthread
+
+ifeq ($(USE_AESNI),yes)
+	CPU_FLAGS = -maes -DAESNI
+endif