fix building on up-to-date Ubuntu

glx-bare/Makefile

@@ -1,8 +1,10 @@
-
 TARGET := glx-bare
-LDFLAGS := -lGL -lX11
+LIBS := -lGL -lX11
 
 all: $(TARGET)
 
+$(TARGET): $(TARGET).c
+	$(CC) -o $@ $^ $(LIBS)
+
 clean:
 	-rm -f *.o $(TARGET)

glx-dbl-bare/Makefile

@@ -1,8 +1,10 @@
-
 TARGET := glx-dbl-bare
-LDFLAGS := -lGL -lX11
+LIBS := -lGL -lX11
 
 all: $(TARGET)
 
+$(TARGET): $(TARGET).c
+	$(CC) -o $@ $^ $(LIBS)
+
 clean:
 	-rm -f *.o $(TARGET)