nfc_nci_example: Switch to C++

Our custom UNUSED_ARGUMENT macro was redundant with the sys/defs.h
__unused macro, so it needed to be removed.  But rather than
switch to __unused, we opt to switch this code to C++, so we can
comment out parameter names to silence compiler warnings about
unused arguments.

The switch to C++ requires casting the result of calloc.  We
also change our function argument indentation per our C++
style rules while we're in here.

Test: Compiled and confirmed no compiler warnings.

Change-Id: Ibd0eef7787843597917c3e0e71bdd772f6e9e876
diff --git a/modules/nfc-nci/Android.bp b/modules/nfc-nci/Android.bp
index 90d2a28..f4ef64e 100644
--- a/modules/nfc-nci/Android.bp
+++ b/modules/nfc-nci/Android.bp
@@ -16,7 +16,7 @@
     name: "nfc_nci.default",
     relative_install_path: "hw",
     proprietary: true,
-    srcs: ["nfc_nci_example.c"],
+    srcs: ["nfc_nci_example.cpp"],
     shared_libs: [
         "liblog",
         "libcutils",