Log Message:
Work around patch for missing _CHECK_SYMBOL_EXISTS in cmake-3.11 by @tristelo

https://lists.launchpad.net/kicad-developers/msg35240.html

|     To: Wayne Stambaugh <stambaughw@xxxxxxxxx>
|     From: Seth Hillbrand <seth.hillbrand@xxxxxxxxx>
|     Date: Fri, 30 Mar 2018 14:15:45 -0700
|     Cc: KiCad Developers <kicad-developers@xxxxxxxxxxxxxxxxxxx>
| Hi Adam-
|
| You will need to downgrade to CMake 3.10 or lower.  In 3.11, they revised
| the internals of CheckSymbolExists.
|
| Our macro depends on the internal CMake macro _CHECK_SYMBOL_EXISTS (note
| the underscore at the beginning).  In 3.11, they replaced it with
| __CHECK_SYMBOL_EXISTS_IMPL.
|
| -S

@tristelo, again, provided work around as one line patch at
  https://gist.github.com/steleto/15794a8b623577911b115813b7ef0ec3

Thanks,