[pdal] PDAL 2.0.1 build issue

[Howard Butler]

> On Sep 16, 2019, at 10:02 AM, Jim Klassen <klassen.js at gmail.com> wrote:
> After multiple attempts at rummaging around, I think the culprit is in 'cmake/gtest.cmake'.  I suspect that ${gtest_BINARY_DIR} is unset.  Based on comments in 'vendor/gtest/CMakeLists.txt' it appears that it may also use this variable internally.

Interesting. We're definitely doing non-sudo builds on other platforms. I wonder how gtest_BINARY_DIR is getting properly set in those cases.

Howard