Revert "[Compiler-rt][MIPS] Fix cross build for XRAY."

Breaks build:
http://lab.llvm.org:8011/builders/sanitizer-x86_64-linux/builds/4677/steps/build%20with%20ninja/logs/stdio

In file included from compiler-rt/lib/xray/xray_fdr_logging.cc:34:
In file included from compiler-rt/lib/xray/xray_fdr_logging_impl.h:36:
In file included from compiler-rt/lib/xray/xray_flags.h:18:
compiler-rt/lib/xray/../sanitizer_common/sanitizer_flag_parser.h:23:7: error: '__sanitizer::FlagHandlerBase' has virtual functions but non-virtual destructor [-Werror,-Wnon-virtual-dtor]
class FlagHandlerBase {

llvm-svn: 316348