Enable backtrace only on glibc #654

musl doesn't support backtrace

lib/ProxySQL_GloVars.cpp

@@ -16,6 +16,7 @@ void crash_handler(int sig) {
 #ifdef DEBUG
 //	malloc_stats_print(NULL, NULL, "");
 #endif
+#ifdef __GLIBC__
 	void *arr[20];
 	size_t s;
 
@@ -23,6 +24,7 @@ void crash_handler(int sig) {
 
 	fprintf(stderr, "Error: signal %d:\n", sig);
 	backtrace_symbols_fd(arr, s, STDERR_FILENO);
+#endif /* __GLIBC__ */
 //#ifdef SYS_gettid
 	// try to generate a core dump signaling again the thread
 	signal(sig, SIG_DFL);