Add Haryanvi (bgc) (#283)

Autonym according to Ethnologue.

Requested at
https://translatewiki.net/w/i.php?oldid=11465315#Request_for_inclusion_of_Haryanvi_language

data/langdb.yaml

@@ -89,6 +89,7 @@ languages:
   bft: [Arab, [AS], بلتی]
   bfq: [Taml, [AS], படகா]
   bg: [Cyrl, [EU], български]
+  bgc: [Deva, [AS], हरियाणवी]
   bgn: [Arab, [AS, ME], روچ کپتین بلوچی]
  # FIXME - currently says Bhojpuri, but it's a macrolanguage.
   bh: [bho]

data/language-data.json

@@ -532,6 +532,13 @@
             ],
             "български"
         ],
+        "bgc": [
+            "Deva",
+            [
+                "AS"
+            ],
+            "हरियाणवी"
+        ],
         "bgn": [
             "Arab",
             [
@@ -5659,6 +5666,7 @@
             "bho",
             "awa",
             "as",
+            "bgc",
             "mag",
             "mai",
             "hne",