[NFC] Fix build failure in ScopDetection

[ctetreau]

Summary

In some build environments, the C++ compiler is unable to infer the
correct type for the DenseMap::insert in isErrorBlock. Typing out
std::make_pair helps.

[ctetreau]

The old code works for me with visual studio 2019, but fails with clang 7 and clang 12.1.

[redacted]/polly/lib/Analysis/ScopDetection.cpp:1472:29: error: no matching member function for call to 'insert'
  auto It = ErrorBlockCache.insert({{&BB, &R}, false});
            ~~~~~~~~~~~~~~~~^~~~~~
[redacted]/llvm/include/llvm/ADT/DenseMap.h:207:29: note: candidate function not viable: cannot convert initializer list argument to 'const std::pair<tuple<const BasicBlock *, const Region *>, bool>'
  std::pair<iterator, bool> insert(const std::pair<KeyT, ValueT> &KV) {
                            ^
[redacted]/llvm/include/llvm/ADT/DenseMap.h:214:29: note: candidate function not viable: cannot convert initializer list argument to 'std::pair<tuple<const BasicBlock *, const Region *>, bool>'
  std::pair<iterator, bool> insert(std::pair<KeyT, ValueT> &&KV) {
                            ^
[redacted]/llvm/include/llvm/ADT/DenseMap.h:297:8: note: candidate function template not viable: requires 2 arguments, but 1 was provided
  void insert(InputIt I, InputIt E) {
       ^

[Meinersbur]

LGTM

polly/lib/Analysis/ScopDetection.cpp

static bool isErrorBlockImpl(BasicBlock &BB, const Region &R, LoopInfo &LI,
 
   return false;
 }
 
 bool ScopDetection::isErrorBlock(llvm::BasicBlock &BB, const llvm::Region &R) {
   if (!PollyAllowErrorBlocks)
     return false;
 
-  auto It = ErrorBlockCache.insert({{&BB, &R}, false});
+  auto It = ErrorBlockCache.insert({std::make_pair(&BB, &R), false});
   if (!It.second)
     return It.first->getSecond();
 
   bool Result = isErrorBlockImpl(BB, R, LI, DT);
   It.first->second = Result;
   return Result;
 }