[cmake] Remove unused OUTPUT_MAPPING param to configure_lit_site_cfg(). NFC

Looks like it never did anything.
Added in 71deeee

Author: sam-mccall

llvm/cmake/modules/AddLLVM.cmake

@@ -1614,15 +1614,12 @@ string(CONCAT LLVM_LIT_PATH_FUNCTION
 # path back to absolute form. This makes it possible to move a build directory
 # containing lit.cfg.py files from one machine to another.
 function(configure_lit_site_cfg site_in site_out)
-  cmake_parse_arguments(ARG "" "" "MAIN_CONFIG;OUTPUT_MAPPING;PATHS" ${ARGN})
+  cmake_parse_arguments(ARG "" "" "MAIN_CONFIG;PATHS" ${ARGN})
 
   if ("${ARG_MAIN_CONFIG}" STREQUAL "")
     get_filename_component(INPUT_DIR ${site_in} DIRECTORY)
     set(ARG_MAIN_CONFIG "${INPUT_DIR}/lit.cfg")
   endif()
-  if ("${ARG_OUTPUT_MAPPING}" STREQUAL "")
-    set(ARG_OUTPUT_MAPPING "${site_out}")
-  endif()
 
   foreach(c ${LLVM_TARGETS_TO_BUILD})
     set(TARGETS_BUILT "${TARGETS_BUILT} ${c}")

llvm/utils/lit/CMakeLists.txt

@@ -4,8 +4,6 @@
 configure_lit_site_cfg(
   "${CMAKE_CURRENT_SOURCE_DIR}/tests/lit.site.cfg.in"
   "${CMAKE_CURRENT_BINARY_DIR}/lit.site.cfg"
-  OUTPUT_MAPPING
-  "${CMAKE_CURRENT_BINARY_DIR}/tests/lit.site.cfg"
   )
 
 # Lit's test suite creates output files next to the sources which makes the