package/rsync: force HAVE_C99_VSNPRINTF to "yes"

We know the system will have a modern-enough C library that implements
the required snprintf() functionality. Since the configure stage can't
detect the system's capabilities (because it is cross-compiling), let's
hard-code the decision.

As a result, rsync won't be linking in its own copy of snprintf().

Signed-off-by: Markus Mayer <mmayer@broadcom.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
(cherry picked from commit 0b17cd017e8b946d718c81f0e38fd570e6a6bc0d)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/rsync/rsync.mk

@@ -11,6 +11,9 @@ RSYNC_LICENSE_FILES = COPYING
 RSYNC_CPE_ID_VENDOR = samba
 RSYNC_SELINUX_MODULES = rsync
 RSYNC_DEPENDENCIES = zlib popt
+# We know that our C library is modern enough for C99 vsnprintf(). Since
+# configure can't detect this, we tell configure that vsnprintf() is safe.
+RSYNC_CONF_ENV = rsync_cv_HAVE_C99_VSNPRINTF=yes
 RSYNC_CONF_OPTS = \
 	--with-included-zlib=no \
 	--with-included-popt=no \