[DebugInfo, CallSites, test] Fix use of undef FileCheck var

[thopre]

Summary

Clang test CodeGen/debug-info-extern-call.c tries to check for the
absence of a sequence of instructions with several CHECK-NOT with one of
those directives using a variable defined in another. However CHECK-NOT
are checked independently so that is using a variable defined in a
pattern that should not occur in the input.

This commit removes the CHECK-NOT for the retained line attribute
definition since the CHECK-NOT on the compile unit will already check
that there is no retained lines.

clang/test/CodeGen/debug-info-extern-call.c

 // RUN:   | FileCheck %s -check-prefix=DECLS-FOR-EXTERN
 //
 // Do not emit a subprogram for extern decls when entry values are disabled and
 // the tuning is not set to gdb.
 //
 // RUN: %clang -g -O2 -target x86_64-none-linux-gnu -gsce -S -emit-llvm %s -o - \
 // RUN:   | FileCheck %s -check-prefix=NO-DECLS-FOR-EXTERN
 
-// DECLS-FOR-EXTERN-NOT: !DICompileUnit({{.*}}retainedTypes: ![[RETTYPES:[0-9]+]]
-// DECLS-FOR-EXTERN-NOT: ![[RETTYPES]] = !{
+// DECLS-FOR-EXTERN-NOT: !DICompileUnit({{.*}}retainedTypes: !{{[0-9]+}}
 // DECLS-FOR-EXTERN: !DISubprogram(name: "fn1"
 // DECLS-FOR-EXTERN-NOT: !DISubprogram(name: "memcmp"
 // DECLS-FOR-EXTERN-NOT: !DISubprogram(name: "__some_reserved_name"
 
 // NO-DECLS-FOR-EXTERN-NOT: !DISubprogram(name: "fn1"
 // NO-DECLS-FOR-EXTERN-NOT: !DISubprogram(name: "memcmp"
 // NO-DECLS-FOR-EXTERN-NOT: !DISubprogram(name: "__some_reserved_name"