configure: bump year

Happy new year!

(cherry picked from commit bddf31ba7570325dd2c8d033eae3d0dd74127f96)
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
diff --git a/configure b/configure
index a1818dc..abb6009 100755
--- a/configure
+++ b/configure
@@ -6703,7 +6703,7 @@
 #define FFMPEG_CONFIG_H
 #define FFMPEG_CONFIGURATION "$(c_escape $FFMPEG_CONFIGURATION)"
 #define FFMPEG_LICENSE "$(c_escape $license)"
-#define CONFIG_THIS_YEAR 2017
+#define CONFIG_THIS_YEAR 2018
 #define FFMPEG_DATADIR "$(eval c_escape $datadir)"
 #define AVCONV_DATADIR "$(eval c_escape $datadir)"
 #define CC_IDENT "$(c_escape ${cc_ident:-Unknown compiler})"