Add option for architecture in Makefile

In this merge request:

• Add an option to add gcc architecture option in main Makefile (-m32, -m64, etc.)
• Use a more idiomatic way to call sub Makefiles

Makefile

+# ARCH_OPT is the gcc architecture option (probably -m32 or -m64)
+export ARCH_OPT="-m32"
+MAKE="make"
 
 build:
-	cd ./psys/src; make
-	cd ./log/src; make
+	$(MAKE) -C psys/src
+	$(MAKE) -C log/src
 
 
 clean:
-	cd log/src; make clean
-	cd psys/src; make clean
+	$(MAKE) -C psys/src clean
+	$(MAKE) -C log/src clean