[NFC][Driver] Require shell for spirv-tools-err.c

The env PATH='' won't work on windows.

Author: sys-ce-bb

clang/test/Driver/spirv-tools-err.c

@@ -1,5 +1,6 @@
 // UNSUPPORTED: spirv-tools
 // REQUIRES: spirv-registered-target
+// REQUIRES: shell
 
 // RUN: env PATH='' not %clang -o /dev/null --target=spirv64 --save-temps -v %s 2>&1 | FileCheck %s