[opaque pointer type] Pass GlobalAlias the actual pointer type rather than decomposing it into pointee type + address space

Many of the callers already have the pointer type anyway, and for the
couple of callers that don't it's pretty easy to call PointerType::get
on the pointee type and address space.

This avoids LLParser from using PointerType::getElementType when parsing
GlobalAliases from IR.

llvm-svn: 236160

llvm/lib/Bitcode/Reader/BitcodeReader.cpp

@@ -3041,8 +3041,7 @@ std::error_code BitcodeReader::ParseModule(bool Resume,
         return Error("Invalid type for value");
 
       auto *NewGA =
-          GlobalAlias::create(PTy->getElementType(), PTy->getAddressSpace(),
-                              getDecodedLinkage(Record[2]), "", TheModule);
+          GlobalAlias::create(PTy, getDecodedLinkage(Record[2]), "", TheModule);
       // Old bitcode files didn't have visibility field.
       // Local linkage must have default visibility.
       if (Record.size() > 3 && !NewGA->hasLocalLinkage())