gtk+-1.2.10: i686-pc-mingw32-gcc: error: unrecognized command line option '-rdynamic'

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Hello,

I am on a Linux 32 bit operating system (Slackware 14.1) and I have a cross-compiler based on:
- binutils-2.24.51
- gcc-4.9.1
- mingwrt-lib-3.20.2
- w32api-3.17.2

When I try to cross-compile a GTK+ application I do:
$ i686-pc-mingw32-gcc `/usr/i686-pc-mingw32/bin/gtk-config --cflags --libs` helloworld.c -o helloworld
i686-pc-mingw32-gcc: error: unrecognized command line option '-rdynamic'

As you can see, there is an error.
It is because the -rdynamic seems to not be a recognized option for my cross-compiler.

Here is the output of "/usr/i686-pc-mingw32/bin/gtk-config --cflags --libs":
$ /usr/i686-pc-mingw32/bin/gtk-config --cflags --libs
-I/usr/i686-pc-mingw32/include/gtk-1.2 -I/usr/include/glib-1.2 -I/usr/lib/glib/include
-L/usr/i686-pc-mingw32/lib -lgtk -lgdk -L/usr/lib -rdynamic -lgmodule -lglib -ldl -lXext -lX11 -lm

What is the meaning of this "-rdynamic" option?
Why the "/usr/i686-pc-mingw32/bin/gtk-config" script gives me this "-rdynamic" option whereas it is not 
recognized by my cross-compiler?

Thank you.
Best regards.