Update the epa_build configuration of tk so that it works on MinGW/MSYS.
Update the epa_build configuration of tk so that it works on MinGW/MSYS.

Tested by: Alan W. Irwin <airwin@users.sourceforge.net> on
MinGW/MSYS/Wine-1.6.1 for the epa_build project with
-DBUILD_THE_BUILDTOOLS=ON using the build_tk target.

N.B. this test shows that Tk builds without issues on MinGW/MSYS
against the installed Tcl epa_build result, but the test
does not include run-time testing.

svn path=/trunk/; revision=12919

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