[PATCH] Fix msvc_gendef.pl for aarch64 (Windows on Arm)

[kenji uno]

I'm going to build psqlODBC (Arm64X binaries) for use with Windows 11 on
Arm.

The problem is that the `msvc_gendef.pl` generates the wrong `postgres.def`
for aarch64 (Windows).

Currently, for aarch64, the preceding underscore is removed like for x86.
However, the expected functionality for aarch64 is the same as for x64:
keep the preceding underscore.

This causes linker errors such as:

> postgres.def : error LNK2001: unresolved external symbol
brin_parallel_build_main
[C:\repos\postgresql-17.0\build-last-try-3\src\backend\22e3565@
@postgres@exe.vcxproj]

Example from src/backend/access/brin/brin.c:

> /*
>  * Perform work within a launched parallel process.
>  */
> void
> _brin_parallel_build_main(dsm_segment *seg, shm_toc *toc)
> {
>   // ...
> }

The attached file is a patch to fix this issue.

-- 
kenji uno (h8mas...@gmail.com)

 src/tools/msvc_gendef.pl | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/tools/msvc_gendef.pl b/src/tools/msvc_gendef.pl
index 404076dbbc..c23320b1d2 100644
--- a/src/tools/msvc_gendef.pl
+++ b/src/tools/msvc_gendef.pl
@@ -122,7 +122,7 @@ sub writedef
 
                # Strip the leading underscore for win32, but not x64
                $f =~ s/^_//
-                 unless ($arch eq "x86_64");
+                 unless ($arch eq 'x86_64' || $arch eq 'aarch64');
 
                # Emit just the name if it's a function symbol, or emit the name
                # decorated with the DATA option for variables.
@@ -143,7 +143,7 @@ sub writedef
 sub usage
 {
        die("Usage: msvc_gendef.pl --arch <arch> --deffile <deffile> --tempdir 
<tempdir> files-or-directories\n"
-                 . "    arch: x86 | x86_64\n"
+                 . "    arch: x86 | x86_64 | aarch64\n"
                  . "    deffile: path of the generated file\n"
                  . "    tempdir: directory for temporary files\n"
                  . "    files or directories: object files or directory 
containing object files\n"
@@ -160,7 +160,7 @@ GetOptions(
        'tempdir:s' => \$tempdir,) or usage();
 
 usage("arch: $arch")
-  unless ($arch eq 'x86' || $arch eq 'x86_64');
+  unless ($arch eq 'x86' || $arch eq 'x86_64' || $arch eq 'aarch64');
 
 my @files;