build: re-enable namespace-specific tests

fx.collections/test/numbers.c

@@ -1,11 +1,12 @@
-#include <fx/ds/number.h>
+#include <fx/double.h>
 #include <stdio.h>
 
 int main(void)
 {
-	fx_number *number = fx_number_create_float(6.8);
+	fx_double *d = fx_double_create(6.8);
+
+	printf("double=%lf\n", fx_double_get_value(d));
+	fx_double_unref(d);
 
-	printf("number=%zd\n", FX_NUMBER_IVAL(number));
-	fx_number_unref(number);
 	return 0;
 }