just build relevant source and use xxx_main functions.
build system: add a special case when we have exactly one applet enabled
(makes "true", "false", "basename" REALLY tiny).
getopt32: do not use stdio.
function old new delta
getopt32 1385 1412 +27
make_device 1187 1200 +13
basename_main 120 127 +7
tcpudpsvd_main 1922 1926 +4
testcmd 5 - -5
echocmd 5 - -5
fuser_main 1243 1231 -12
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(add/remove: 0/2 grow/shrink: 4/1 up/down: 51/-22) Total: 29 bytes
