[Bug 49438] New: Wine on ARM64 fails with "could not exec the wine loader" unless --enable-win64 is used

[WineHQ Bugzilla]

https://bugs.winehq.org/show_bug.cgi?id=49438

Bug ID: 49438
           Summary: Wine on ARM64 fails with "could not exec the wine
                    loader" unless --enable-win64 is used
           Product: Wine
           Version: 5.11
          Hardware: aarch64
                OS: Linux
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: ntdll
          Assignee: [e-mail]
          Reporter: [e-mail]
      Distribution: ---

I've been building Wine on ARM64 (Ubuntu 19.10 64-bit on Raspberry Pi 4).

Since 67bc4a6d765941d830477f749ab7b0697f1488b2 ("ntdll: Don't use libwine
during the Unix library initialization."), Wine fails with "could not exec the
wine loader" unless '--enable-win64' is passed to configure. Before that
commit, I was using configure without any options.

The problem looks to be that in dlls/ntdll/unix/server.c, 'loader/wine64' or
'loader/wine' is chosen based on the size of a pointer (is_win64). And unless
'--enable-win64' is used, 'loader/wine' is built, but it tries to exec
'loader/wine64'.

I'm not sure what the best fix for this is. Require a win64 build when 64-bit
code is being built? The 'configure' help text should also be updated.

Configure options now needed:
'./configure --enable-win64 CC=clang'