Temporarily disable ffead (#5815)

The last two runs in the Citrine environment failed because of
problems induced by ffead.  We don't know that ffead is doing
anything wrong -- even if it is, the TFB toolset is to blame for
letting that ruin the run -- but we would like to continue
benchmarking other frameworks while we figure this out.

frameworks/C++/ffead-cpp/benchmark_config.json

@@ -23,7 +23,7 @@
 			"display_name": "ffead-cpp-mongo",
 			"notes": "mongodb redis",
 			"versus": "",
-			"tags": []
+			"tags": ["broken"]
 		},
 		"nginx-mysql": {
 			"json_url": "/te-benchmark-um/json",
@@ -66,7 +66,7 @@
 			"display_name": "ffead-cpp-lithium",
 			"notes": "",
 			"versus": "",
-			"tags": []
+			"tags": ["broken"]
 		},
 		"cinatra": {
 			"json_url": "/te-benchmark-um/json",
@@ -85,7 +85,7 @@
 			"display_name": "ffead-cpp-cinatra",
 			"notes": "",
 			"versus": "",
-			"tags": []
+			"tags": ["broken"]
 		},
 		"drogon": {
 			"json_url": "/te-benchmark-um/json",
@@ -104,7 +104,7 @@
 			"display_name": "ffead-cpp-drogon",
 			"notes": "",
 			"versus": "",
-			"tags": []
+			"tags": ["broken"]
 		},
 		"libreactor": {
 			"json_url": "/te-benchmark-um/json",
@@ -123,7 +123,7 @@
 			"display_name": "ffead-cpp-libreactor",
 			"notes": "",
 			"versus": "",
-			"tags": []
+			"tags": ["broken"]
 		},
 		"crystal-h2o": {
 			"json_url": "/te-benchmark-um/json",
@@ -142,7 +142,7 @@
 			"display_name": "ffead-cpp-crystal-h2o",
 			"notes": "",
 			"versus": "",
-			"tags": []
+			"tags": ["broken"]
 		},
 		"rust-actix": {
 			"json_url": "/te-benchmark-um/json",
@@ -161,7 +161,7 @@
 			"display_name": "ffead-cpp-rust-actix",
 			"notes": "",
 			"versus": "",
-			"tags": []
+			"tags": ["broken"]
 		},
 		"go-gnet": {
 			"json_url": "/te-benchmark-um/json",
@@ -180,7 +180,7 @@
 			"display_name": "ffead-cpp-go-gnet",
 			"notes": "",
 			"versus": "",
-			"tags": []
+			"tags": ["broken"]
 		},
 		"v-picov": {
 			"json_url": "/te-benchmark-um/json",
@@ -199,7 +199,7 @@
 			"display_name": "ffead-cpp-v-vweb",
 			"notes": "",
 			"versus": "",
-			"tags": []
+			"tags": ["broken"]
 		},
 		"java-firenio": {
 			"json_url": "/te-benchmark-um/json",
@@ -218,7 +218,7 @@
 			"display_name": "ffead-cpp-java-firenio",
 			"notes": "",
 			"versus": "",
-			"tags": []
+			"tags": ["broken"]
 		},
 		"crystal-http": {
 			"json_url": "/te-benchmark-um/json",
@@ -237,7 +237,7 @@
 			"display_name": "ffead-cpp-crystal-http",
 			"notes": "",
 			"versus": "",
-			"tags": []
+			"tags": ["broken"]
 		},
 		"rust-hyper": {
 			"json_url": "/te-benchmark-um/json",
@@ -256,7 +256,7 @@
 			"display_name": "ffead-cpp-rust-hyper",
 			"notes": "",
 			"versus": "",
-			"tags": []
+			"tags": ["broken"]
 		},
 		"rust-thruster": {
 			"json_url": "/te-benchmark-um/json",
@@ -275,7 +275,7 @@
 			"display_name": "ffead-cpp-rust-thruster",
 			"notes": "",
 			"versus": "",
-			"tags": []
+			"tags": ["broken"]
 		},
 		"go-fasthttp": {
 			"json_url": "/te-benchmark-um/json",
@@ -294,7 +294,7 @@
 			"display_name": "ffead-cpp-go-fasthttp",
 			"notes": "",
 			"versus": "",
-			"tags": []
+			"tags": ["broken"]
 		},
 		"v-vweb": {
 			"json_url": "/te-benchmark-um/json",
@@ -313,7 +313,7 @@
 			"display_name": "ffead-cpp-v-vweb",
 			"notes": "",
 			"versus": "",
-			"tags": []
+			"tags": ["broken"]
 		},
 		"java-rapidoid": {
 			"json_url": "/te-benchmark-um/json",
@@ -332,7 +332,7 @@
 			"display_name": "ffead-cpp-java-rapidoid",
 			"notes": "",
 			"versus": "",
-			"tags": []
+			"tags": ["broken"]
 		},
 		"java-wizzardo-http": {
 			"json_url": "/te-benchmark-um/json",
@@ -351,7 +351,7 @@
 			"display_name": "ffead-cpp-java-wizzardo-http",
 			"notes": "",
 			"versus": "",
-			"tags": []
+			"tags": ["broken"]
 		},
 		"rust-rocket": {
 			"json_url": "/te-benchmark-um/json",