[libomptarget] Regression when `LLVM_LIBRARY_OUTPUT_INTDIR` is not set

[tuliom]

Is this if-else doing the opposite of the intended behavior?
It uses LLVM_LIBRARY_OUTPUT_INTDIR when it is not set, leading to the following kind of error:

CMake Error at libomptarget/DeviceRTL/CMakeLists.txt:304 (set_target_properties):
  set_target_properties called with incorrect number of arguments.

I started seeing this error after #73705 .

[tuliom]

@jhuber6 could you take a look at this, please?

[llvmbot]

@llvm/issue-subscribers-openmp

Author: Tulio Magno Quites Machado Filho (tuliom)

Is [this if-else](https://github.com/llvm/llvm-project/commit/0ec4b82cfddbe0c7c7eb4b3486f55139f56d5f16#diff-898240fd97677719cdcafe8300e5d2cef2c1807aac768de03577f2057ef91630R27-R31) doing the opposite of the intended behavior? It uses `LLVM_LIBRARY_OUTPUT_INTDIR` when it is not set, leading to the following kind of error:

CMake Error at libomptarget/DeviceRTL/CMakeLists.txt:304 (set_target_properties):
  set_target_properties called with incorrect number of arguments.

I started seeing this error after #73705 .

[nikic]

Ping @jhuber6

[jhuber6]

Sorry, I've been on break. I probably forgot to put quotation marks around it to handle the empty case.