Android: Allow opening/getting files relative to downloads directory

src/common/cd_image_chd.cpp

@@ -279,7 +279,7 @@ bool CDImageCHD::Open(const char* filename, Common::Error* error)
   m_lba_count = disc_lba;
   AddLeadOutIndex();
 
-  m_sbi.LoadSBI(FileSystem::ReplaceExtension(filename, "sbi").c_str());
+  m_sbi.LoadSBIFromImagePath(filename);
 
   return Seek(1, Position{0, 0, 0});
 }