configure.ac: Don't require vpx now that we don't build the webm encoder
diff --git a/configure.ac b/configure.ac
index 30c12b4..231a024 100644
--- a/configure.ac
+++ b/configure.ac
@@ -217,7 +217,7 @@
 AM_CONDITIONAL(BUILD_WCAP_TOOLS, test x$enable_wcap_tools = xyes)
 if test x$enable_wcap_tools = xyes; then
   AC_DEFINE([BUILD_WCAP_TOOLS], [1], [Build the wcap tools])
-  PKG_CHECK_MODULES(WCAP, [cairo vpx])
+  PKG_CHECK_MODULES(WCAP, [cairo])
   WCAP_LIBS="$WCAP_LIBS -lm"
 fi