Makefile for CGI program using SQLite library
First impressions
This is clear and easy to read, and follows conventions well.

Use more built-ins
You can use more of Make's built-in rules.  For example, this rule can be omitted entirely:
sqlfuncgi.o: sqlfuncgi.c
    $(CC) -o $@ $^ -c $(CFLAGS)

If you add $(SQLITEDIR) to the VPATH, the sqlite3.o rule becomes simply
sqlite3.o: CFLAGS += -Os

And the link rule can use the built-in LINK.c variable:
sqlfun.cgi: sqlfuncgi.o sqlite3.o
    $(LINK.c) -o $@ $^  $(LDLIBS)


Special targets
Good use of .PHONY.  We probably also want .DELETE_ON_ERROR to ensure that if any command fails, its partially-written outputs don't hang around and appear to be made

Portability improvement
We can use Make's predefined $(RM) in place of rm -f.