switch from CHECK-NOT to implicit-check-not="Skipped pattern"

more future-proof

Author: JL2210

llvm/test/TableGen/GlobalISelEmitter-implicit-defs.td

@@ -1,9 +1,8 @@
-// RUN: llvm-tblgen -gen-global-isel -warn-on-skipped-patterns -I %p/../../include -I %p/Common %s -o /dev/null 2>&1 < %s | FileCheck %s
+// RUN: llvm-tblgen -gen-global-isel -warn-on-skipped-patterns -I %p/../../include -I %p/Common %s -o /dev/null 2>&1 < %s | FileCheck %s --implicit-check-not="Skipped pattern"
 
 include "llvm/Target/Target.td"
 include "GlobalISelEmitterCommon.td"
 
-// CHECK-NOT: Skipped pattern: Src pattern result has 1 def(s) without the HasNoUse predicate set to true but Dst MI has no def
 // CHECK: Skipped pattern: Pattern defines a physical register
 let Uses = [B0], Defs = [B0] in
 def tst1 : I<(outs), (ins), [(set B0, (add B0, 1))]>;