[cmake] Remove dead code. NFC.

Author: gottesmm

cmake/modules/SwiftXcodeSupport.cmake

@@ -25,15 +25,6 @@ function(escape_path_for_xcode config path result_var_name)
   set("${result_var_name}" "${result}" PARENT_SCOPE)
 endfunction()
 
-function(get_imported_library_prefix outvar target prefix)
-  string(FIND "${target}" "${prefix}" ALREADY_HAS_PREFIX)
-  if (ALREADY_HAS_PREFIX)
-    set(${outvar} "" PARENT_SCOPE)
-  else()
-    set(${outvar} "${prefix}" PARENT_SCOPE)
-  endif()
-endfunction()
-
 function(check_imported_target_has_imported_configuration target config)
   get_target_property(IMPORTED_CONFIGS_LIST ${target} IMPORTED_CONFIGURATIONS)
   if ("${IMPORTED_CONFIGS_LIST}" STREQUAL "NOTFOUND")