Fix COMPILE_VSTI guard scope: always read gm.dls into lpGMDLSBuffer

[Copilot]

The #ifdef COMPILE_VSTI guard at line 263 was incorrectly wrapping the entire file-open and ReadFile block, preventing lpGMDLSBuffer from being populated in non-VSTi builds. Only the new RIFF parsing logic should be conditional on COMPILE_VSTI.

Changes

• Removed #ifdef COMPILE_VSTI from before the CreateFileA/ReadFile/CloseHandle block — file reading now occurs under #ifdef _WIN32 / #ifndef GMDLS_SKIP only
• Moved #ifdef COMPILE_VSTI to guard only the new DLS RIFF parsing logic (the do { … } while(0) block) that follows the file read

// Before: entire block guarded
#ifdef COMPILE_VSTI
    HANDLE hFile = CreateFileA(...);
    if (hFile != INVALID_HANDLE_VALUE)
    {
        ReadFile(hFile, lpGMDLSBuffer, ...);
        CloseHandle(hFile);
        // new parsing logic ...
    }
#endif

// After: only parsing guarded
HANDLE hFile = CreateFileA(...);
if (hFile != INVALID_HANDLE_VALUE)
{
    ReadFile(hFile, lpGMDLSBuffer, ...);
    CloseHandle(hFile);
#ifdef COMPILE_VSTI
    // new parsing logic ...
#endif
}