#57 Remove "su root" from makefile

[kbinani]

"su root" is hard-coded in makefile.
This may spoil flexibility about an install destination.

--- a/makefile
+++ b/makefile
@@ -20,5 +20,5 @@ test :
    cd test ; make -f posix.mak

 install :

-   cd install ; su root -c "make -f install.mak" 
+   cd install ; make -f install.mak