[embedded] Make linux-rng-support.c friendly to compiling in both C and C++ mode

Author: kubamracek

test/embedded/Inputs/linux-rng-support.c

@@ -5,8 +5,16 @@
 
 #ifdef __linux__ 
 
+#ifdef __cplusplus
+extern "C"
+#endif
 ssize_t getrandom(void *buf, size_t len, unsigned int flags);
 
+#ifdef __cplusplus
+extern "C"
+#endif
+void arc4random_buf(void *buf, size_t nbytes);
+
 void arc4random_buf(void *buf, size_t nbytes) {
   while (nbytes > 0) {
     ssize_t actual_nbytes = 0;