[XRay] Mark test unsupported on armhf

Tbis addresses a buildbot failure now that these tests actually run more
broadly.

error: ALWAYSINSTR: expected string not found in input
// ALWAYSINSTR: {{.*function-name:.*main.*}}
                ^
<stdin>:1:1: note: scanning from here

Author: boomanaiden154

compiler-rt/test/xray/TestCases/Posix/always-never-instrument.cpp

@@ -12,6 +12,8 @@
 
 // REQUIRES: built-in-llvm-tree
 
+// UNSUPPORTED: armhf-linux
+
 // NOINSTR-NOT: {{.*__xray_NeverInstrumented.*}}
 int __xray_NeverInstrumented() {
   return 0;