Here you find a patched version of MinGW libintl dll 0.17-1 with builtin relocation support for executables. With this DLL your programs are automatically relocatable. No need to add relocation code to your program source code.
Libintl is part of the gettext (see also here) package. The patch was ported from the GnuWin32 port of libintl, which also has builtin relocation support. See here.
At the moment the relocation support is only active if you compile with MinGW for Windows. If you compile for Unix/Linux/Cygwin the functionality is unchanged.
This patch has been submitted to the MinGW project tracker. See here
Upstream gettext maintainers have been notified on May 27 2010 via bug-gnu-gettext@gnu.org, but they have not responded yet.