Remove more cleanly generated configuration file.

example/Makefile

@@ -17,7 +17,7 @@ all: config
 config:
 	printf "#include <gmp.h>\nint main(void){mpz_t z; mpz_init(z); return 0;}\n" > config-test.c
 	$(CC) $(CFLAGS) $(CPPFLAGS) $(LDFLAGS)  -I$(GMP_DIR)/include -L$(GMP_DIR)/lib -lgmp config-test.c -o config-test.exe 2> /dev/null && echo "-DHAVE_GMP=1  -I$(GMP_DIR)/include -L$(GMP_DIR)/lib -lgmp" > config || echo "-DHAVE_GMP=0" > config
-	$(RM) config-test.*
+	$(RM) config-test.c config-test.exe
 
 clean:
 	$(RM) *.exe *.s *~ *.o ./a.dat config