Don't assume malloc sets errno to ENOMEM.

Although many implementations (including glibc) set errno on failure,
this is not required by the C standard.

src/irda.c

@@ -83,7 +83,7 @@ irda_socket_open (irda_t **out, dc_context_t *context)
 #ifdef _WIN32
 		SYSERROR (context, ERROR_OUTOFMEMORY);
 #else
-		SYSERROR (context, errno);
+		SYSERROR (context, ENOMEM);
 #endif
 		return -1; // ENOMEM (Not enough space)
 	}

src/serial_posix.c

@@ -137,7 +137,7 @@ serial_open (serial_t **out, dc_context_t *context, const char* name)
 	// Allocate memory.
 	serial_t *device = (serial_t *) malloc (sizeof (serial_t));
 	if (device == NULL) {
-		SYSERROR (context, errno);
+		SYSERROR (context, ENOMEM);
 		return -1; // ENOMEM (Not enough space)
 	}