[asan] Set flags appropriately for RTEMS

[waltl]

Summary

Disable both unmap_shadow_on_exit and protect_shadow_gap.

[kcc]

LGTM

compiler-rt/trunk/lib/asan/asan_flags.cc

#endif
   }
   CHECK_LE((uptr)common_flags()->malloc_context_size, kStackTraceMax);
   CHECK_LE(f->min_uar_stack_size_log, f->max_uar_stack_size_log);
   CHECK_GE(f->redzone, 16);
   CHECK_GE(f->max_redzone, f->redzone);
   CHECK_LE(f->max_redzone, 2048);
   CHECK(IsPowerOfTwo(f->redzone));
   CHECK(IsPowerOfTwo(f->max_redzone));
+  if (SANITIZER_RTEMS) {
+    CHECK(!f->unmap_shadow_on_exit);
+    CHECK(!f->protect_shadow_gap);
+  }
 
   // quarantine_size is deprecated but we still honor it.
   // quarantine_size can not be used together with quarantine_size_mb.
   if (f->quarantine_size >= 0 && f->quarantine_size_mb >= 0) {
     Report("%s: please use either 'quarantine_size' (deprecated) or "
            "quarantine_size_mb, but not both\n", SanitizerToolName);
     Die();
   }

compiler-rt/trunk/lib/asan/asan_flags.inc

ASAN_FLAG(
     "needs to attach gdb).")
 ASAN_FLAG(
     int, sleep_after_init, 0,
     "Number of seconds to sleep after AddressSanitizer is initialized. "
     "Useful for debugging purposes (e.g. when one needs to attach gdb).")
 ASAN_FLAG(bool, check_malloc_usable_size, true,
           "Allows the users to work around the bug in Nvidia drivers prior to "
           "295.*.")
-ASAN_FLAG(bool, unmap_shadow_on_exit, false,
+ASAN_FLAG(bool, unmap_shadow_on_exit, !SANITIZER_RTEMS,
           "If set, explicitly unmaps the (huge) shadow at exit.")
-ASAN_FLAG(bool, protect_shadow_gap, true, "If set, mprotect the shadow gap")
+ASAN_FLAG(bool, protect_shadow_gap, !SANITIZER_RTEMS,
+          "If set, mprotect the shadow gap")
 ASAN_FLAG(bool, print_stats, false,
           "Print various statistics after printing an error message or if "
           "atexit=1.")
 ASAN_FLAG(bool, print_legend, true, "Print the legend for the shadow bytes.")
 ASAN_FLAG(bool, print_scariness, false,
           "Print the scariness score. Experimental.")
 ASAN_FLAG(bool, atexit, false,
           "If set, prints ASan exit stats even after program terminates "