[Sanitizers] Add *SAN_OPTIONS to possibly_dangerous_env_vars

[filcab]

Summary

This way, if they're set when running ninja check-ubsan (or another
sanitizer), they get cleared before we start invoking the programs.

[samsonov]

OK, let's try this... I've looked at the buildbots and it looks like we're only setting *SAN_OPTIONS environment variables when we're running regular (not sanitizer) tests.

compiler-rt/trunk/test/lit.common.cfg

elif compiler_id == 'GNU':
   config.cxx_mode_flags = ["-x c++"]
   config.debug_info_flags = ["-g"]
 else:
   lit_config.fatal("Unsupported compiler id: %r" % compiler_id)
 # Add compiler ID to the list of available features.
 config.available_features.add(compiler_id)
 
 # Clear some environment variables that might affect Clang.
-possibly_dangerous_env_vars = ['COMPILER_PATH', 'RC_DEBUG_OPTIONS',
+possibly_dangerous_env_vars = ['ASAN_OPTIONS', 'DFSAN_OPTIONS', 'LSAN_OPTIONS',
+                               'MSAN_OPTIONS', 'UBSAN_OPTIONS',
+                               'COMPILER_PATH', 'RC_DEBUG_OPTIONS',
                                'CINDEXTEST_PREAMBLE_FILE', 'LIBRARY_PATH',
                                'CPATH', 'C_INCLUDE_PATH', 'CPLUS_INCLUDE_PATH',
                                'OBJC_INCLUDE_PATH', 'OBJCPLUS_INCLUDE_PATH',
                                'LIBCLANG_TIMING', 'LIBCLANG_OBJTRACKING',
                                'LIBCLANG_LOGGING', 'LIBCLANG_BGPRIO_INDEX',
                                'LIBCLANG_BGPRIO_EDIT', 'LIBCLANG_NOTHREADS',
                                'LIBCLANG_RESOURCE_USAGE',
                                'LIBCLANG_CODE_COMPLETION_LOGGING']