PcapFile: Namespace code under the Common namespace

Brings more common code under the Common namespace.

Source/Core/Common/PcapFile.cpp

@@ -8,6 +8,8 @@
 #include "Common/File.h"
 #include "Common/PcapFile.h"
 
+namespace Common
+{
 namespace
 {
 const u32 PCAP_MAGIC = 0xa1b2c3d4;
@@ -61,3 +63,4 @@ void PCAP::AddPacket(const u8* bytes, size_t size)
   m_fp->WriteBytes(&rec_hdr, sizeof(rec_hdr));
   m_fp->WriteBytes(bytes, size);
 }
+}  // namespace Common