Put libraries in %{_libdir} when building wxGTK RPMs.

Using the default libdir value ${_prefix}/lib is not always appropriate,
notably this takes care of systems using /usr/lib64 instead of /usr/lib.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@65823 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

wxGTK.spec

@@ -140,7 +140,7 @@ fi
 
 mkdir obj-shared
 cd obj-shared
-../configure --prefix=%{_prefix} \
+../configure --prefix=%{_prefix} --libdir=%{_libdir} \
 %if ! %{gtk2}
 			      --with-gtk=1 \
 %else
@@ -158,7 +158,7 @@ cd ..
 
 mkdir obj-static
 cd obj-static
-../configure --prefix=%{_prefix} \
+../configure --prefix=%{_prefix} --libdir=%{_libdir} \
 %if ! %{gtk2}
 			      --with-gtk=1 \
 %else