* build/FindBrotli.cmake: Add a missing BROTLI_VERSION value.

git-svn-id: https://svn.apache.org/repos/asf/serf/trunk@1925984 13f79535-47bb-0310-9956-ffa450edef68

Author: brainy

build/FindBrotli.cmake

@@ -46,6 +46,8 @@ function(_get_brotli_version)
      string(STRIP "${output}" output)
      set(BROTLI_VERSION "${output}" PARENT_SCOPE)
    endif()
+ else()
+   set(BROTLI_VERSION "unknown" PARENT_SCOPE)
  endif()
 endfunction(_get_brotli_version)