Set supported target for asan-use-callbacks test

[thopre]

Summary

Explicitely set x86_64-linux-gnu as a target for asan-use-callbacks
clang test since some target do not support -fsanitize=address (e.g.
i386-pc-openbsd). Also remove redundant -fsanitize=address and move
-emit-llvm right after -S.

[vitalybuka]

Why other tests, like CodeGen/asan-strings.c do not need REQUIRES: ?

[vitalybuka]

All but line 1 is LGTM
Line 1 is probably not needed, but I don't know why.

[thopre]

Remove REQUIRES

clang/test/CodeGen/asan-use-callbacks.cpp

-// RUN: %clang -S -fsanitize=address -emit-llvm -o - -fsanitize=address %s \
+// RUN: %clang -target x86_64-linux-gnu -S -emit-llvm -fsanitize=address \
+// RUN:     -o - %s \
 // RUN:     | FileCheck %s --check-prefixes=CHECK-NO-OUTLINE
-// RUN: %clang -S -fsanitize=address -emit-llvm -o - -fsanitize=address %s \
-// RUN:     -fsanitize-address-outline-instrumentation \
+// RUN: %clang -target x86_64-linux-gnu -S -emit-llvm -o - \
+// RUN:     -fsanitize=address %s -fsanitize-address-outline-instrumentation \
 // RUN:     | FileCheck %s --check-prefixes=CHECK-OUTLINE
 
 // CHECK-NO-OUTLINE-NOT: call{{.*}}@__asan_load4
 // CHECK-OUTLINE: call{{.*}}@__asan_load4
 
 int deref(int *p) {
   return *p;
 }