Add libcurl impersonation support in Firefox build

48415a4b00 added impersonation
capabilities to libcurl in the Chrome build. This adds the same
capabilities to the Firefox build as well.

curl-impersonate.patch generated from
https://github.com/lwthiker/curl/commit/b30b245b722dbe9765615e3f316e9a7dab99bbf9

chrome/Dockerfile

@@ -73,8 +73,7 @@ RUN mkdir out && \
 
 # Re-compile libcurl dynamically
 RUN cd ${CURL_VERSION} && \
-    ./configure --enable-versioned-symbols \
-                --with-openssl=/build/boringssl/build \
+    ./configure --with-openssl=/build/boringssl/build \
                 --with-nghttp2=/usr/local \
                 LIBS="-pthread" \
                 CFLAGS="-I/build/boringssl/build" \