[DFSan] Remove use of setarch in dfsan test.

Use of setarch Was added by
llvm@f93c2b6

Running the test now it doesn't seem necessary because:

1) Explicitly only x86_64 is supported for dfsan.

2) https://reviews.llvm.org/D111522 makes it less flakey.

Differential Revision: https://reviews.llvm.org/D121439

Author: browneee

compiler-rt/test/dfsan/release_shadow_space.c

@@ -1,7 +1,7 @@
-// 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
-// DFSAN_OPTIONS=no_huge_pages_for_shadow=false RUN: %clang_dfsan %s -DORIGIN_TRACKING -mllvm -dfsan-track-origins=1 -o %t && setarch `uname -m` -R %run %t
-// DFSAN_OPTIONS=no_huge_pages_for_shadow=true RUN: %clang_dfsan %s -DORIGIN_TRACKING -mllvm -dfsan-track-origins=1 -o %t && setarch `uname -m` -R %run %t
+// 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 -DORIGIN_TRACKING -mllvm -dfsan-track-origins=1 -o %t && %run %t
+// DFSAN_OPTIONS=no_huge_pages_for_shadow=true RUN: %clang_dfsan %s -DORIGIN_TRACKING -mllvm -dfsan-track-origins=1 -o %t && %run %t
 //
 // REQUIRES: x86_64-target-arch