Add dlfcn-win32 to third_party

third_party/dlfcn-win32/Makefile

+#
+# dlfcn-win32 Makefile
+#
+include config.mak
+
+ifeq ($(BUILD_SHARED),yes)
+        TARGETS+=libdl.dll
+        SHFLAGS+=-Wl,--out-implib,libdl.dll.a
+        INSTALL+=shared-install
+endif
+ifeq ($(BUILD_STATIC),yes)
+        TARGETS+=libdl.a
+        INSTALL+=static-install
+endif
+ifeq ($(BUILD_MSVC),yes)
+        SHFLAGS+=-Wl,--output-def,libdl.def
+        INSTALL+=lib-install
+endif
+
+all: $(TARGETS)
+
+dlfcn.o:
+        $(CC) -o dlfcn.o -c dlfcn.c -Wall -O3 -fomit-frame-pointer
+
+libdl.a: dlfcn.o
+        $(AR) cru libdl.a dlfcn.o
+        $(RANLIB) libdl.a
+
+libdl.dll: dlfcn.o
+        $(CC) $(SHFLAGS) -shared -o libdl.dll dlfcn.o
+        $(LIBCMD) /machine:i386 /def:libdl.def
+
+shared-install:
+        mkdir -p $(DESTDIR)$(prefix)/bin
+        cp libdl.dll $(DESTDIR)$(prefix)/bin
+        $(STRIP) $(DESTDIR)$(prefix)/bin/libdl.dll
+        mkdir -p $(DESTDIR)$(libdir)
+        cp libdl.dll.a $(DESTDIR)$(libdir)
+        mkdir -p $(DESTDIR)$(incdir)
+        cp dlfcn.h $(DESTDIR)$(incdir)
+
+static-install:
+        mkdir -p $(DESTDIR)$(libdir)
+        cp libdl.a $(DESTDIR)$(libdir)
+        mkdir -p $(DESTDIR)$(incdir)
+        cp dlfcn.h $(DESTDIR)$(incdir)
+
+lib-install:
+        mkdir -p $(DESTDIR)$(libdir)
+        cp libdl.lib $(DESTDIR)$(libdir)
+
+install: $(INSTALL)
+
+test.exe:
+        $(CC) -o test.exe test.c -L. -ldl
+
+testdll.dll:
+        $(CC) -shared -o testdll.dll testdll.c
+
+test: $(TARGETS) test.exe testdll.dll
+        test.exe
+
+clean::
+        rm -f dlfcn.o libdl.dll libdl.a libdl.def libdl.dll.a libdl.lib libdl.exp test.exe testdll.dll
+
+distclean: clean
+        rm -f config.mak
+
+.PHONY: clean distclean install test