Link zlib statically for windows (#35)

* Add zlib 1.2.11 sources

* link zlib statically for windows

third_party/zlib/contrib/ada/zlib.gpr

@@ -0,0 +1,20 @@
+project Zlib is
+
+   for Languages use ("Ada");
+   for Source_Dirs use (".");
+   for Object_Dir use ".";
+   for Main use ("test.adb", "mtest.adb", "read.adb", "buffer_demo");
+
+   package Compiler is
+      for Default_Switches ("ada") use ("-gnatwcfilopru", "-gnatVcdfimorst", "-gnatyabcefhiklmnoprst");
+   end Compiler;
+
+   package Linker is
+      for Default_Switches ("ada") use ("-lz");
+   end Linker;
+
+   package Builder is
+      for Default_Switches ("ada") use ("-s", "-gnatQ");
+   end Builder;
+
+end Zlib;