Improve gendef.pl diagnostic on failure to open sym file

There have been numerous buildfarm failures but the diagnostic is
currently silent about the reason for failure to open the file. Let's
see if we can get to the bottom of it.

Backpatch to all live branches.

diff --git a/src/tools/msvc/gendef.pl b/src/tools/msvc/gendef.pl
index 96122750f190a4bd5ea19ea507be59e8f8d74761..9b5bc081e16b1c39f51f6879e40355bdc2e91404 100644 (file)
--- a/src/tools/msvc/gendef.pl
+++ b/src/tools/msvc/gendef.pl
@@ -32,7 +32,7 @@ sub dumpsyms
 sub extract_syms
 {
    my ($symfile, $def) = @_;
-   open(my $f, '<', $symfile) || die "Could not open $symfile for $_\n";
+   open(my $f, '<', $symfile) || die "Could not open $symfile for $_: $!\n";
    while (<$f>)
    {