Add "// REQUIRES: OS=linux-gnu"

Author: practicalswift

validation-test/compiler_crashers/28606-swift-typebase-getcanonicaltype.swift

@@ -5,5 +5,6 @@
 // See https://swift.org/LICENSE.txt for license information
 // See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
 
+// REQUIRES: OS=linux-gnu
 // RUN: not --crash %target-swift-frontend %s -emit-ir
 print([.h.h=#keyPath(n&_=(){