[mlir][CMAKE] Fix cross-compilation build

[vinograd47]

Summary

Use MLIR_LINALG_ODS_GEN and MLIR_LINALG_ODS_YAML_GEN variables
instead of MLIR_LINALG_ODS_GEN_EXE and MLIR_LINALG_ODS_YAML_GEN_EXE.
The former are defined in PARENT SCOPE only, so the if condition
is never evaluates to TRUE.

The logic should be the following (taken from tblgen part):

1. TOOL_NAME - CACHE variable (default equal to target name). User can override it to actual executable path.
2. TOOL_NAME_EXE - internal variable, initialized to ${TOOL_NAME} first. In case of cross-compilation (LLVM_USE_HOST_TOOLS == TRUE) if user didn't set own path to native executable via TOOL_NAME variable, CMake will create separate targets to build native tool and will override TOOL_NAME_EXE to the executable produced by this target.
3. TOOL_NAME_TARGET - internal variable, which points to tool target name. If the native tool is built as described above, it will point to the target correspondant to that native tool.

mlir/tools/mlir-linalg-ods-gen/CMakeLists.txt

 
 set(MLIR_LINALG_ODS_GEN mlir-linalg-ods-gen CACHE
     STRING "Native mlir-linalg-ods-gen executable. Saves building one when cross-compiling.")
 
 set(MLIR_LINALG_ODS_GEN_EXE ${MLIR_LINALG_ODS_GEN} PARENT_SCOPE)
 set(MLIR_LINALG_ODS_GEN_TARGET mlir-linalg-ods-gen PARENT_SCOPE)
 
 if(LLVM_USE_HOST_TOOLS)
-  if ("${MLIR_LINALG_ODS_GEN_EXE}" STREQUAL mlir-linalg-ods-gen)
+  if (${MLIR_LINALG_ODS_GEN} STREQUAL "mlir-linalg-ods-gen")
     build_native_tool(mlir-linalg-ods-gen MLIR_LINALG_ODS_GEN_EXE DEPENDS mlir-linalg-ods-gen)
     set(MLIR_LINALG_ODS_GEN_EXE ${MLIR_LINALG_ODS_GEN_EXE} PARENT_SCOPE)
 
     add_custom_target(mlir-linalg-ods-gen-host DEPENDS ${MLIR_LINALG_ODS_GEN_EXE})
     set(MLIR_LINALG_ODS_GEN_TARGET mlir-linalg-ods-gen-host DEPENDS PARENT_SCOPE)
 
     if(NOT LLVM_BUILD_UTILS)
       set_target_properties(mlir-linalg-ods-gen PROPERTIES EXCLUDE_FROM_ALL ON)

 
 set(MLIR_LINALG_ODS_YAML_GEN mlir-linalg-ods-yaml-gen CACHE
   STRING "Native mlir-linalg-ods-yaml-gen executable. Saves building one when cross-compiling.")
 
 set(MLIR_LINALG_ODS_YAML_GEN_EXE ${MLIR_LINALG_ODS_YAML_GEN} PARENT_SCOPE)
 set(MLIR_LINALG_ODS_YAML_GEN_TARGET mlir-linalg-ods-yaml-gen PARENT_SCOPE)
 
 if(LLVM_USE_HOST_TOOLS)
-if ("${MLIR_LINALG_ODS_YAML_GEN_EXE}" STREQUAL mlir-linalg-ods-yaml-gen)
+  if (${MLIR_LINALG_ODS_YAML_GEN} STREQUAL "mlir-linalg-ods-yaml-gen")
     build_native_tool(mlir-linalg-ods-yaml-gen MLIR_LINALG_ODS_YAML_GEN_EXE DEPENDS mlir-linalg-ods-yaml-gen)
     set(MLIR_LINALG_ODS_YAML_GEN_EXE ${MLIR_LINALG_ODS_YAML_GEN_EXE} PARENT_SCOPE)
 
     add_custom_target(mlir-linalg-ods-yaml-gen-host DEPENDS ${MLIR_LINALG_ODS_YAML_GEN_EXE})
     set(MLIR_LINALG_ODS_YAML_GEN_TARGET mlir-linalg-ods-yaml-gen-host DEPENDS PARENT_SCOPE)
 
     if(NOT LLVM_BUILD_UTILS)
       set_target_properties(mlir-linalg-ods-yaml-gen PROPERTIES EXCLUDE_FROM_ALL ON)
     endif()
   endif()
 endif()