Update make dependency for elf/module/nxflat/posix_spawn/sotest/thttpd examples which make use of
mksymtab.sh. This could avoid them built twice in 'make depend' and 'make all' which would result
in file truncated build break. Now only build once by 'make all'.
Change-Id: I5d8f1ebbf73e3b12d7d2118f1f51b4233d0ed007
Signed-off-by: liuhaitao <liuhaitao@xiaomi.com>
