config.mak.uname: add arc4random to the cygwin build

The arc4random_buf() function has been available in cygwin since
about 2016 (somewhere in the v2.x branch). Set the CSPRNG_METHOD
build variable to 'arc4random', in the cygwin section, to enable
the use of this cryptographically-secure pseudorandom number
function. Note that the autoconf and new meson builds also enable
this function.

Signed-off-by: Ramsay Jones <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: ramsay-jones

config.mak.uname

@@ -254,6 +254,7 @@ ifeq ($(uname_O),Cygwin)
 	HAVE_CLOCK_GETTIME = YesPlease
 	HAVE_CLOCK_MONOTONIC = YesPlease
 	HAVE_SYSINFO = YesPlease
+	CSPRNG_METHOD = arc4random
 	HAVE_ALLOCA_H = YesPlease
 	NEEDS_LIBICONV = YesPlease
 	NO_FAST_WORKING_DIRECTORY = UnfortunatelyYes