Fix detection of netinet/tcp.h on Cygwin.

Author: DDoSolitary

Diff for: cmake/configure.cmake

@@ -46,7 +46,11 @@ check_function_exists(memset HAVE_MEMSET)
 
 check_include_files(netdb.h HAVE_NETDB_H)
 check_include_files(netinet/in.h HAVE_NETINET_IN_H)
-check_include_files(netinet/tcp.h HAVE_NETINET_TCP_H)
+if (CYGWIN)
+    check_include_files("sys/types.h;netinet/tcp.h" HAVE_NETINET_TCP_H)
+else ()
+    check_include_files(netinet/tcp.h HAVE_NETINET_TCP_H)
+endif ()
 check_include_files(linux/tcp.h HAVE_LINUX_TCP_H)
 check_include_files(net/if.h HAVE_NET_IF_H)
 check_include_files(pcre.h HAVE_PCRE_H)