[OpenMPIRBuilder] Add a constructor to ReductionInfo to appease gcc5

Otherwise, it produces wrong code for brace initializers.

Author: ftynse

llvm/include/llvm/Frontend/OpenMP/OMPIRBuilder.h

@@ -500,6 +500,12 @@ class OpenMPIRBuilder {
 
   /// Information about an OpenMP reduction.
   struct ReductionInfo {
+    ReductionInfo(Value *Variable, Value *PrivateVariable,
+                  ReductionGenTy ReductionGen,
+                  AtomicReductionGenTy AtomicReductionGen)
+        : Variable(Variable), PrivateVariable(PrivateVariable),
+          ReductionGen(ReductionGen), AtomicReductionGen(AtomicReductionGen) {}
+
     /// Returns the type of the element being reduced.
     Type *getElementType() const {
       return Variable->getType()->getPointerElementType();