ssedetect: call __builtin_cpu_supports() only if supported

Some compilers don't support the __builtin_cpu_supports built-in,
so let's make them able to compile the project anyway.

Change-Id: I0c90402d8e4c9f196c54b066ff30891c8de3ad2b
diff --git a/Transceiver52M/osmo-trx.cpp b/Transceiver52M/osmo-trx.cpp
index 1c0ceb1..31a99cf 100644
--- a/Transceiver52M/osmo-trx.cpp
+++ b/Transceiver52M/osmo-trx.cpp
@@ -397,18 +397,26 @@
 
 #ifdef HAVE_SSE3
 	printf("Info: SSE3 support compiled in");
+#ifdef HAVE___BUILTIN_CPU_SUPPORTS
 	if (__builtin_cpu_supports("sse3"))
 		printf(" and supported by CPU\n");
 	else
 		printf(", but not supported by CPU\n");
+#else
+	printf(", but runtime SIMD detection disabled\n");
+#endif
 #endif
 
 #ifdef HAVE_SSE4_1
 	printf("Info: SSE4.1 support compiled in");
+#ifdef HAVE___BUILTIN_CPU_SUPPORTS
 	if (__builtin_cpu_supports("sse4.1"))
 		printf(" and supported by CPU\n");
 	else
 		printf(", but not supported by CPU\n");
+#else
+	printf(", but runtime SIMD detection disabled\n");
+#endif
 #endif
 
 	convolve_init();