isobuilder: write M2_RAW sectors verbatim again

The CD-ROM rewrite merge brought back an EDC/ECC recompute in
writeSectorAt's M2_RAW case, which overwrites the tail of a raw payload
whose subheader says form 1. M2_RAW means the caller owns those bytes,
as everywhere else in the builder.

src/supportpsx/iso9660-builder.cc

@@ -81,7 +81,6 @@ PCSX::IEC60908b::MSF PCSX::ISO9660Builder::writeSectorAt(const uint8_t* sectorDa
             msf.toBCD(ptr + 12);
             ptr[15] = 2;
             memcpy(ptr + 16, sectorData, 2336);
-            compute_edcecc(ptr);
             m_out->writeAt(std::move(slice), lba * IEC60908b::FRAMESIZE_RAW);
             break;
         case IEC60908b::SectorMode::M2_FORM1: