[gobject-introspection] Fix scanning libraries with no GObjects and linker using --as-needed

[Robert Ancell <rancell src gnome org>]

commit b055ddb89da79b5ae22c37ec79ab5009d7db4603
Author: Robert Ancell <robert ancell canonical com>
Date:   Thu May 2 00:52:42 2013 -0700

    Fix scanning libraries with no GObjects and linker using --as-needed
    
    https://bugzilla.gnome.org/show_bug.cgi?id=699442

 giscanner/dumper.py |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)
---
diff --git a/giscanner/dumper.py b/giscanner/dumper.py
index 1ef1f4b..992eb76 100644
--- a/giscanner/dumper.py
+++ b/giscanner/dumper.py
@@ -319,6 +319,10 @@ class DumpCompiler(object):
             else:
                 args.append('-Wl,-rpath=.')
 
+        # Ensure libraries are always linked as we are going to use ldd to work out their names later
+        if not libtool and self._pkgconfig_msvc_flags == '':
+            args.append('-Wl,--no-as-needed')
+
         for library in self._options.libraries:
             # Visual C++: We have the needed .lib files now, and we need to link
             # to .lib files, not the .dll as the --library option specifies the