Make padding consistent on all operating systems

Seeking beyond the end of the stream doesn't necesarily pad it. Some versions of operating systems or platforms might yield different behavior. On my system, this occasionally failed, especially when the positive seek offset from the end of the stream was large. Changed any padding behavior with an actual cheap Pad() call to make sure this will never be an issue.

src/logic/pakfile.cpp

@@ -160,7 +160,7 @@ void CPakFileBuilder::AddStreamingDataEntry(PakStreamSetEntry_s& block, const ui
 	if (paddedSize > block.dataSize)
 	{
 		const size_t paddingRemainder = paddedSize - block.dataSize;
-		out.SeekPut(paddingRemainder, std::ios::cur);
+		out.Pad(paddingRemainder);
 	}
 
 	size_t& nextOffsetCounter = isMandatory ? m_nextMandatoryStarpakOffset : m_nextOptionalStarpakOffset;
@@ -868,10 +868,5 @@ void CPakFileBuilder::BuildFromMap(const string& mapPath)
 	Log("Written pak file \"%s\" with %zu assets, totaling %zd bytes.\n",
 		m_pakFilePath.c_str(), GetAssetCount(), totalPakSize);
 
-	// if we had pages which we ended up padding out to match the alignment,
-	// then we need to seek back to the end of the file; SeekPut only writes
-	// up to len if we either write after it again, or close the stream when
-	// the SeekPut cursor is at that location.
-	out.SeekPut(totalPakSize);
 	out.Close();
 }

src/logic/pakpage.cpp

@@ -356,7 +356,7 @@ void CPakPageBuilder::WritePageData(BinaryIO& out) const
 				// - pad out the previous asset to align our current asset.
 				// - pad out the current asset to its full aligned size.
 				// - pad out the page to its full aligned size.
-				out.SeekPut(lump.size, std::ios::cur);
+				out.Pad(lump.size);
 			}
 		}
 	}