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 8ccaab35519e472117d60243ce4cb5ff87cd71cd..04b0bbe6c79aad3469bbd763574caad892395eb9 100644 (file)
--- a/src/tools/msvc/gendef.pl
+++ b/src/tools/msvc/gendef.pl
@@ -29,7 +29,7 @@ sub dumpsyms
 sub extract_syms
 {
    my ($symfile, $def) = @_;
-   open(F, "<$symfile") || die "Could not open $symfile for $_\n";
+   open(F, "<$symfile") || die "Could not open $symfile for $_: $!\n";
    while ()
    {