configure: fix --disable-external

conditional "USE_VULKAN" was never defined

diff --git a/configure.ac b/configure.ac
index 0b97fcb..7d756fe 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -3528,6 +3528,7 @@ AM_CONDITIONAL(USE_WEBRTCDSP, false)
 AM_CONDITIONAL(USE_OPENH264, false)
 AM_CONDITIONAL(USE_X265, false)
 AM_CONDITIONAL(USE_DTLS, false)
+AM_CONDITIONAL(USE_VULKAN, false)
 
 fi dnl of EXT plugins