[BUGFIX] FLUIDTEMPLATE - Serialization of 'Closure' is not allowed

When using FLUIDTEMPLATE and COA_INT or USER_INT on the same
level and partials are used in the Fluid template, then there
will be Closures. COA_INT and USER_INT are going to serialize
the cObj, which fails when a Closure shall be processed.

Since the Closures have been collected in $cObj->contentObjects
the fix is to use a cloned version of the cObj which does not
contain these contentObjects anymore for COA_INT and USER_INT.

Change-Id: I5c1f9b01caef1df5077955bd7fa6e879e41ca854
Fixes: #36820
Related: #32295
Releases: 6.0, 4.7, 4.6
Reviewed-on: http://review.typo3.org/10979
Reviewed-by: Susanne Moog
Tested-by: Susanne Moog
Reviewed-by: Helmut Hummel
Tested-by: Helmut Hummel
Reviewed-by: Benjamin Mack
Tested-by: Benjamin Mack