Add bot config for ClangToTiOS

BUG=452726

Review URL: https://codereview.chromium.org/1145723003

Cr-Commit-Position: refs/heads/master@{#330767}

ios/build/bots/chromium.fyi/ClangToTiOS.json

+{
+  "owners": [
+    "hans"
+  ],
+  "comments": [
+    "Clang tip-of-tree builder for iOS"
+  ],
+  "xcode version": "6.2",
+  "GYP_DEFINES": {
+    "chromium_ios_signing": "0",
+    "clang_use_chrome_plugins": "0",
+    "target_subarch": "arm32",
+    "werror": ""
+  },
+  "env": {
+    "LLVM_FORCE_HEAD_REVISION": "YES"
+  },
+  "compiler": "ninja",
+  "configuration": "Release",
+  "sdk": "iphoneos8.2",
+  "tests": [
+  ]
+}