18.06 builds are totally different than the bleeding edge master. There are separate buildbots for master, 18.06 and old 17.01 branches. So, no relevance to the LD_LIBRARY_PATH ucert problem in master, that was mentioned by OP.
@rmandrad
Master, the bleeding edge, can be broken sometimes if some commits broke things. Master is meant for development & testing by users/developers who are willing to accept the occasional brokenness.
Right now master has problem with new ucert, as discussed in
- Latest openwrt git cant build (08.08.2018, ucert - libjson-c.so)
- https://github.com/openwrt/openwrt/pull/1259
- in developer mailing list: https://www.mail-archive.com/openwrt-devel@lists.openwrt.org/msg43040.html
But even that can be bypassed with the patch proposal in that PR. Builds can be done again, once you have created the ucert keys once, e.g by applying that patch from the PR.
Likely a fix will come soon, or the ucert based signing will be reverted for a while.