[compiler-rt] Fix check for cross-compiling

When checking if we are cross-compiling, use `CMAKE_HOST_SYSTEM_NAME`
rather than `CMAKE_HOST_SYSTEM` which seems to have the full version
number attached.

Reviewed By: smeenai

Differential Revision: https://reviews.llvm.org/D132130

compiler-rt/CMakeLists.txt

@@ -127,11 +127,11 @@ set(COMPILER_RT_BINARY_DIR ${CMAKE_CURRENT_BINARY_DIR})
 
 pythonize_bool(LLVM_ENABLE_PER_TARGET_RUNTIME_DIR)
 
-# We support running instrumented tests when we're not cross compiling
+# We support running instrumented tests when we're not cross-compiling
 # and target a UNIX-like system or Windows.
 # We can run tests on Android even when we are cross-compiling.
-if(("${CMAKE_HOST_SYSTEM}" STREQUAL "${CMAKE_SYSTEM}" AND (UNIX OR WIN32)) OR ANDROID
-   OR COMPILER_RT_EMULATOR)
+if(("${CMAKE_HOST_SYSTEM_NAME}" STREQUAL "${CMAKE_SYSTEM_NAME}" AND (UNIX OR WIN32))
+   OR ANDROID OR COMPILER_RT_EMULATOR)
   option(COMPILER_RT_CAN_EXECUTE_TESTS "Can we execute instrumented tests" ON)
 else()
   option(COMPILER_RT_CAN_EXECUTE_TESTS "Can we execute instrumented tests" OFF)