Remove nonexistent file

This commit was SVN r26687.

contrib/Makefile.am

@@ -90,7 +90,6 @@ EXTRA_DIST = \
         platform/lanl/tlcc2/optimized-panasas.conf \
 	platform/snl/portals4-m5 \
 	platform/snl/portals4-orte \
-	platform/snl/portals4-shmem \
         platform/win32/CMakeModules/check_bool.cmake \
         platform/win32/CMakeModules/check_c_inline.cmake \
         platform/win32/CMakeModules/check_c_type_exists.cmake \