change Makefile to be stricter

-Og enables better detection of bugs that would only occur in optimized
compilations and allows for slightly lesser than -O1 optimization that
does not interfere with debugging.

Makefile

@@ -1,13 +1,14 @@
-CFLAGS = -g -Wall -Wextra -Werror
+CC = gcc
+CFLAGS = -Og -Wall -Wextra -Werror
 
 objects = main.o input.o output.o encode.o
 
 b64 : $(objects)
-	cc -o b64 $(objects)
+	$(CC) -o b64 $(objects)
 
 main.o input.o : input.h
-main.o output.o : output.h
 main.o encode.o : encode.h
+main.o output.o : output.h
 
 .PHONY : clean
 clean :