Create /bin/kcpfpg symlink on kcpfpg install

tcpborphserver3 relies upon the kcpfpg utility being available as
`/bin/kcpfpg`, but the kcpfpg Makefile installs it into `$(PREFIX)/bin`.
Since the #define in the tcpborphserver3 code cannot predict what the
user might use for PREFIX, I decided to keep the #define unchanged (for
backwards compatibility) and just create `/bin/kcpfpg` as a symlink to
`$(PREFIX)/bin/kcpfpg`.  This will break if the user sets PREFIX to an
empty string or `/` since it will try to create a symlink to itself.

fpg/Makefile

@@ -23,5 +23,8 @@ $(EXE): $(OBJ)
 clean:
 	$(RM) $(OBJ) core $(EXE)
 
+# Create symlink in /bin so that the upload_to_ram_and_program
+# command in tcpborphserver3 will work.
 install: all
 	$(INSTALL) $(EXE) $(PREFIX)/bin
+	ln -sf $(PREFIX)/bin/$(EXE) /bin/$(EXE)

tcpborphserver3/Makefile

@@ -31,10 +31,9 @@ clean:
 %.o: %.c
 	$(CC) $(CFLAGS) -c $< -o $@ $(INC)
 
+# Ensure that kcpfpg gets installed
 install: all
-	# Ensure that kcpfpg in installed in /usr so
-	# that upload_to_ram_and_program will work!
-	$(MAKE) -C ../fpg PREFIX=/usr $@
+	$(MAKE) -C ../fpg $@
 	$(INSTALL) $(SERVER) $(PREFIX)/sbin
 
 test-bof: bof.c