Add clant configuration

Older versions of include-what-you-use do not understand stdint.h for some
reason, so add some local configuration for this for now.

.clant.json

@@ -0,0 +1,4 @@
+{
+  "version": "1.0.0",
+  "mapping_files": [".includes.imp"]
+}

.includes.imp

@@ -0,0 +1,6 @@
+[
+  { "symbol": [ "int64_t",  "private", "<stdint.h>", "public" ] },
+  { "symbol": [ "uint32_t", "private", "<stdint.h>", "public" ] },
+  { "symbol": [ "uint64_t", "private", "<stdint.h>", "public" ] },
+  { "symbol": [ "uint8_t",  "private", "<stdint.h>", "public" ] },
+]