Add zlib to the web build, fix an error in CThread...

thirdparty/zlib/CMakeLists.txt

@@ -0,0 +1,22 @@
+cmake_minimum_required(VERSION 3.16.0)
+project(zlib)
+
+# Build
+add_library(zlib STATIC
+    adler32.c
+	compress.c
+	crc32.c
+	deflate.c
+	gzclose.c
+	gzlib.c
+	gzread.c
+	gzwrite.c
+	infback.c
+	inffast.c
+	inflate.c
+	inftrees.c
+	trees.c
+	uncompr.c
+	zutil.c
+)
+target_include_directories(zlib PUBLIC .)

thirdparty/zlib/gzguts.h

@@ -37,6 +37,8 @@
 
 #if defined(__TURBOC__) || defined(_MSC_VER) || defined(_WIN32)
 #  include <io.h>
+#else
+#  include <unistd.h>
 #endif
 
 #if defined(_WIN32)