Missing case in blt_patch_target and blt_determine_scope

[white238]

We are missing a case where we need to downscope from PUBLIC to INTERFACE in a couple places.

Truncated output from user:

-- [foo property] 'foo' is a CMake target
-- [foo property] IMPORTED: TRUE
-- [foo property] NAME: foo
-- [foo property] TYPE: STATIC_LIBRARY

Error:

CMake Error at /blt/cmake/BLTMacros.cmake:467 (target_link_libraries):
  IMPORTED library can only be used with the INTERFACE keyword of
  target_link_libraries
Call Stack (most recent call first):
  cmake/thirdparty/SetupAxomThirdParty.cmake:214 (blt_patch_target)
  cmake/CMakeBasics.cmake:20 (include)
  CMakeLists.txt:126 (include)