Rename all *.cpp files to *.cc to follow new style

Change-Id: Ia79ee09348e67ff4a1712ee11a1e8480180a2623
diff --git a/hci/BUILD.gn b/hci/BUILD.gn
index 35a0b78..a99021c 100644
--- a/hci/BUILD.gn
+++ b/hci/BUILD.gn
@@ -46,13 +46,13 @@
 executable("net_test_hci") {
   testonly = true
   sources = [
-    "//osi/test/AllocationTestHarness.cpp",
-    "//osi/test/AlarmTestHarness.cpp",
-    "test/hci_hal_h4_test.cpp",
-    "test/hci_hal_mct_test.cpp",
-    "test/hci_layer_test.cpp",
-    "test/low_power_manager_test.cpp",
-    "test/packet_fragmenter_test.cpp",
+    "//osi/test/AllocationTestHarness.cc",
+    "//osi/test/AlarmTestHarness.cc",
+    "test/hci_hal_h4_test.cc",
+    "test/hci_hal_mct_test.cc",
+    "test/hci_layer_test.cc",
+    "test/low_power_manager_test.cc",
+    "test/packet_fragmenter_test.cc",
   ]
 
   include_dirs = [