[build] Make a number of static libraries build with -fvisibility=hidden

ZX-1895 #comment
Test: CQ

Change-Id: Id3252fcb1de5a6f6e1897da86fba92e2be9d0319

[ulib] Expose inspector library outside zircon.

I would like to use this functionality for CP-59 in Garnet as a static
library (since it will be small).

CP-59: #progress

TEST=fx full-build

Change-Id: Ib35450afd8ee9f369c28e08278f1939f92f9c04e

[ulib][inspector] Make a library of crashlogger's backtracer

Change-Id: I7de0ac4d17bdaeb447a9eca00698cd4f91df9117