Upgrade jsoncpp to 1.9.4

Bug: 170642246
Change-Id: Id1fae5a1b6421117f923c616718ee4b3571231e0
diff --git a/.clang-tidy b/.clang-tidy
new file mode 100644
index 0000000..be3d06a
--- /dev/null
+++ b/.clang-tidy
@@ -0,0 +1,11 @@
+---
+Checks:          'google-readability-casting,modernize-deprecated-headers,modernize-loop-convert,modernize-use-auto,modernize-use-default-member-init,modernize-use-using,readability-else-after-return,readability-redundant-member-init,readability-redundant-string-cstr'
+WarningsAsErrors: ''
+HeaderFilterRegex: ''
+AnalyzeTemporaryDtors: false
+FormatStyle:     none
+CheckOptions:    
+  - key:             modernize-use-using.IgnoreMacros
+    value:           '0'
+...
+