CI: travis-ci: switch BoringSSL builds to ninja

using ninja instead of make speed up build by 40 sec
diff --git a/scripts/build-ssl.sh b/scripts/build-ssl.sh
index 0940f3c..34eee9b 100755
--- a/scripts/build-ssl.sh
+++ b/scripts/build-ssl.sh
@@ -100,8 +100,8 @@
         if [ -d build ]; then rm -rf build; fi
 	mkdir build
 	cd build
-	cmake -DCMAKE_BUILD_TYPE=release -DBUILD_SHARED_LIBS=1 ..
-	make
+	cmake  -GNinja -DCMAKE_BUILD_TYPE=release -DBUILD_SHARED_LIBS=1 ..
+	ninja
 
 	rm -rf ${SSL_LIB} || exit 0
 	rm -rf ${SSL_INC} || exit 0