config.mak.uname: add HAVE_GETDELIM to the cygwin section

Cygwin has provided the getdelim() function as far back as (at least)
2011. The autoconf and meson builds enable the use of this symbol.
In order to have the same configuration for autoconf, meson and make,
enable the HAVE_GETDELIM build variable in the cygwin section of the
config.mak.uname file.

Signed-off-by: Ramsay Jones <ramsay@ramsayjones.plus.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: ramsay-jones

config.mak.uname

@@ -250,6 +250,7 @@ ifeq ($(uname_O),Cygwin)
                 endif
         endif
 	HAVE_DEV_TTY = YesPlease
+	HAVE_GETDELIM = YesPlease
 	HAVE_ALLOCA_H = YesPlease
 	NEEDS_LIBICONV = YesPlease
 	NO_FAST_WORKING_DIRECTORY = UnfortunatelyYes