[SYCL][NFC] Re-enable sycl.c test on Windows

Re-enabling for testing purposes.  Am unable to reproduce locally.

Author: mdtoguchi

clang/test/Driver/sycl.c

@@ -1,6 +1,3 @@
-// Failing on Windows - temporarily disable
-// REQUIRES: system-linux
-
 // RUN: %clang -### -fsycl -c %s 2>&1 | FileCheck %s --check-prefix=ENABLED
 // RUN: %clang -### -fsycl %s 2>&1 | FileCheck %s --check-prefix=ENABLED
 // RUN: %clang -### -fno-sycl -fsycl %s 2>&1 | FileCheck %s --check-prefix=ENABLED