[sanitizer] Disable ASLR for release_shadow_space

[zatrazz]

Summary

On aarch64 with kernel 4.12.13 the test sporadically fails with

RSS at start: 1564, after mmap: 103964, after mmap+set label: 308768, \
after fixed map: 206368, after another mmap+set label: 308768, after \
munmap: 206368
release_shadow_space.c.tmp: [...]/release_shadow_space.c:80: int \
main(int, char **): Assertion `after_fixed_mmap <= before + delta' failed.

It seems on some executions the memory is not fully released, even
after munmap. And it also seems that ASLR is hurting it by adding
some fragmentation, by disabling it I could not reproduce the issue
in multiple runs.

[stephan.yichao.zhao]

LGTM since dfsan focuses on linux. Thank you for helping resolve the issue.

compiler-rt/test/dfsan/release_shadow_space.c

-// DFSAN_OPTIONS=no_huge_pages_for_shadow=false RUN: %clang_dfsan %s -o %t && %run %t
-// DFSAN_OPTIONS=no_huge_pages_for_shadow=true RUN: %clang_dfsan %s -o %t && %run %t
+// DFSAN_OPTIONS=no_huge_pages_for_shadow=false RUN: %clang_dfsan %s -o %t && setarch `uname -m` -R %run %t
+// DFSAN_OPTIONS=no_huge_pages_for_shadow=true RUN: %clang_dfsan %s -o %t && setarch `uname -m` -R %run %t
 
 #include <assert.h>
 #include <sanitizer/dfsan_interface.h>
 #include <stdbool.h>
 #include <stdio.h>
 #include <string.h>
 #include <sys/mman.h>
 #include <unistd.h>