perf(init): stop using a mutex during search paths

* I don't think there's any IO threading here that would warrant
  the need for mutexing this, as all platforms now use a single IO thread
* this greatly improves initialization time when scanning paths

Author: mastercoms

src/filesystem/basefilesystem.h

@@ -580,10 +580,8 @@ abstract_class CBaseFileSystem : public CTier1AppSystem< IFileSystem >
 
 			if ( *ppszFilename && !Q_IsAbsolutePath( *ppszFilename ) )
 			{
-				// Copy paths to minimize mutex lock time
-				pFileSystem->m_SearchPathsMutex.Lock();
+				// Copy to keep filesystem intact
 				CopySearchPaths( pFileSystem->m_SearchPaths );
-				pFileSystem->m_SearchPathsMutex.Unlock();
 
 				pFileSystem->FixUpPath ( *ppszFilename, m_Filename, sizeof( m_Filename ) );
 			}
@@ -611,10 +609,8 @@ abstract_class CBaseFileSystem : public CTier1AppSystem< IFileSystem >
 			{
 				m_pathID =  UTL_INVAL_SYMBOL;
 			}
-			// Copy paths to minimize mutex lock time
-			pFileSystem->m_SearchPathsMutex.Lock();
+			// Copy to keep filesystem intact
 			CopySearchPaths( pFileSystem->m_SearchPaths );
-			pFileSystem->m_SearchPathsMutex.Unlock();
 			m_Filename[0] = '\0';
 		}