chore(vendor): add Windows cflags parity block to tree-sitter-c/binding.gyp

c's binding.gyp used an unconditional `cflags_c: ["-std=c11"]`, while
kotlin/swift gate MSVC flags behind an `OS=='win'` condition (/std:c11 /utf-8).
Inert today (no non-ASCII bytes in c's parser.c, and node-gyp ignores cflags_c
on MSVC anyway), but align the three so a future source-build fallback on
Windows behaves consistently.

gitnexus/vendor/tree-sitter-c/binding.gyp

@@ -12,8 +12,17 @@
         "bindings/node/binding.cc",
         "src/parser.c",
       ],
-      "cflags_c": [
-        "-std=c11",
+      "conditions": [
+        ["OS!='win'", {
+          "cflags_c": [
+            "-std=c11",
+          ],
+        }, { # OS == "win"
+          "cflags_c": [
+            "/std:c11",
+            "/utf-8",
+          ],
+        }],
       ],
     }
   ]