Change cpp to c file ahead of further extensions to the fuzzing test
harness.  This simplifies building afl-fuzz or with just C tools, but could be made C++ again if needed in the future.

Test: build and ran libFuzzer test
Bug: 239630493
Change-Id: I8873883ab5b91f36b707cd9d05856aa4c9c222bd
diff --git a/fuzzing/Android.bp b/fuzzing/Android.bp
index a9c27e3..09b1f4a 100644
--- a/fuzzing/Android.bp
+++ b/fuzzing/Android.bp
@@ -6,7 +6,7 @@
 cc_fuzz {
     name: "libfdt_fuzzer",
     srcs: [
-        "libfdt_fuzzer.cpp",
+        "libfdt_fuzzer.c",
     ],
     static_libs: [
         "libfdt",