ITS#4621 only check winsock.h if using MinGW

configure.in

@@ -852,10 +852,13 @@ AC_CHECK_HEADERS(	\
 	termios.h		\
 	unistd.h		\
 	utime.h			\
-	winsock.h		\
-	winsock2.h		\
 )
 
+dnl Only check Winsock on MinGW
+if test "$ac_cv_mingw32" = yes ; then
+	AC_CHECK_HEADERS( winsock.h winsock2.h )
+fi
+
 AC_CHECK_HEADERS( resolv.h, [], [],
 [$ac_includes_default
 #include <netinet/in.h>
@@ -887,9 +890,7 @@ fi
 dnl The following is INTENTIONALLY scripted out because shell does not
 dnl support variable names with the '@' character, which is what
 dnl autoconf would try to generate if one merely used AC_SEARCH_LIBS
-dnl
-dnl Skip Winsock tests on Cygwin
-if test "$ac_cv_cygwin" != yes && test "$ac_cv_header_winsock_h" = yes; then
+if test "$ac_cv_header_winsock_h" = yes; then
 AC_CACHE_CHECK([for winsock], [ol_cv_winsock],
 save_LIBS="$LIBS"
 for curlib in ws2_32 wsock32; do