NuttX commit 346336bb9e5c9199b82e34d08bf23dd1bc389460 make CONFIG_NET_TCP_READADHEAD unselectable and removed all references to CONFIG_NET_TCP_READHEAD from the the NuttX repositories. However, there was no corresponding removal of CONFIG_NET_TCP_READHEAD from the apps/ repository. As a result, there was logic that depended on the selection of CONFIG_NET_TCP_READHEAD that could never be enabled.
This was found during build testing using the configuration olimex-lpc1766stk/thttpd-binfs. THTTPD was not being build fully because it had dependencies on CONFIG_NET_TCP_READHEAD. There resulted int numerous new warnings and, finally, the error:
(.../apps.examples.thttpd.o): in function `thttp_main':
thttpd_main.c:(.text+0x104): undefined reference to `thttpd_main'
