travis: enable quiche's FFI feature

docs/HTTP3.md

@@ -116,7 +116,7 @@ Build quiche and BoringSSL:
 
      % git clone --recursive https://github.com/cloudflare/quiche
      % cd quiche
-     % cargo build --release --features pkg-config-meta,qlog
+     % cargo build --release --features ffi,pkg-config-meta,qlog
      % mkdir deps/boringssl/src/lib
      % ln -vnf $(find target/release -name libcrypto.a -o -name libssl.a) deps/boringssl/src/lib/
 

scripts/travis/before_script.sh

@@ -121,7 +121,7 @@ if [ "$TRAVIS_OS_NAME" = linux -a "$QUICHE" ]; then
   curl https://sh.rustup.rs -sSf | sh -s -- -y
   source $HOME/.cargo/env
   cd $HOME/quiche
-  cargo build -v --release --features pkg-config-meta,qlog
+  cargo build -v --release --features ffi,pkg-config-meta,qlog
   mkdir -v deps/boringssl/src/lib
   ln -vnf $(find target/release -name libcrypto.a -o -name libssl.a) deps/boringssl/src/lib/
 fi