Change LIBS to LDFLAGS in Makefiles

This is to make it more standard which further allows one to run make on
some other source code, say because they want to try and fix an entry
but forget to update the Makefile. Or if they're the author they can not
worry about it in some cases. But since LDFLAGS is the standard way it
seems better to have the LIBS variable in the Makefile be LDFLAGS.

Maybe there is a reason to not have this and I'm happy to close this in
that case but it does seem better this way so I'm doing this commit.

2001/dgbeards/Makefile

@@ -74,7 +74,7 @@ CFLAGS= ${CSTD} ${CWARN} ${ARCH} ${CDEFINE} ${CINCLUDE} ${OPT}
 
 # Libraries needed to build
 #
-LIBS=
+LDFLAGS=
 
 # C compiler to use
 #
@@ -131,7 +131,7 @@ all: data ${TARGET}
 	supernova deep_magic magic charon pluto
 
 ${PROG}: ${PROG}.c
-	${CC} ${CFLAGS} $< -o $@ ${LIBS}
+	${CC} ${CFLAGS} $< -o $@ ${LDFLAGS}
 
 # alternative executable
 #