Merge pull request #12869 from yashykt/logandroid

extern C for gpr_default_log in android
diff --git a/src/core/lib/support/log_android.cc b/src/core/lib/support/log_android.cc
index 6f1cec5..fed535d 100644
--- a/src/core/lib/support/log_android.cc
+++ b/src/core/lib/support/log_android.cc
@@ -39,8 +39,8 @@
   return ANDROID_LOG_DEFAULT;
 }
 
-void gpr_log(const char *file, int line, gpr_log_severity severity,
-             const char *format, ...) {
+extern "C" void gpr_log(const char *file, int line, gpr_log_severity severity,
+                        const char *format, ...) {
   char *message = NULL;
   va_list args;
   va_start(args, format);
@@ -50,7 +50,7 @@
   free(message);
 }
 
-void gpr_default_log(gpr_log_func_args *args) {
+extern "C" void gpr_default_log(gpr_log_func_args *args) {
   char *final_slash;
   const char *display_file;
   char *output = NULL;