[compiler-rt][HWAsan} Add env prefixes in test

This patch adds env prefixes to some environment variables that get set
inside a hwasan test. This broke when enabling the internal shell on
AArch64 and was not caught as I did not test precommit there.

Author: boomanaiden154

compiler-rt/test/hwasan/TestCases/Linux/fixed-shadow.c

@@ -3,17 +3,17 @@
 // Default compiler instrumentation works with any shadow base (dynamic or fixed).
 // RUN: %clang_hwasan %s -o %t
 // RUN: %run %t
-// RUN: HWASAN_OPTIONS=fixed_shadow_base=263878495698944 %run %t 2>%t.out || (cat %t.out | FileCheck %s)
-// RUN: HWASAN_OPTIONS=fixed_shadow_base=4398046511104 %run %t
+// RUN: env HWASAN_OPTIONS=fixed_shadow_base=263878495698944 %run %t 2>%t.out || (cat %t.out | FileCheck %s)
+// RUN: env HWASAN_OPTIONS=fixed_shadow_base=4398046511104 %run %t
 //
 // If -hwasan-mapping-offset is set, then the fixed_shadow_base needs to match.
 // RUN: %clang_hwasan %s -mllvm -hwasan-mapping-offset=263878495698944 -o %t
-// RUN: HWASAN_OPTIONS=fixed_shadow_base=263878495698944 %run %t 2>%t.out || (cat %t.out | FileCheck %s)
-// RUN: HWASAN_OPTIONS=fixed_shadow_base=4398046511104 not %run %t
+// RUN: env HWASAN_OPTIONS=fixed_shadow_base=263878495698944 %run %t 2>%t.out || (cat %t.out | FileCheck %s)
+// RUN: env HWASAN_OPTIONS=fixed_shadow_base=4398046511104 not %run %t
 
 // RUN: %clang_hwasan %s -mllvm -hwasan-mapping-offset=4398046511104 -o %t
-// RUN: HWASAN_OPTIONS=fixed_shadow_base=4398046511104 %run %t
-// RUN: HWASAN_OPTIONS=fixed_shadow_base=263878495698944 not %run %t
+// RUN: env HWASAN_OPTIONS=fixed_shadow_base=4398046511104 %run %t
+// RUN: env HWASAN_OPTIONS=fixed_shadow_base=263878495698944 not %run %t
 //
 // Note: if fixed_shadow_base is not set, compiler-rt will dynamically choose a
 // shadow base, which has a tiny but non-zero probability of matching the