libstdc++-v3: drop GCC Runtime Library Exception from gen tests

libstdc++-v3: drop GCC Runtime Library Exception from gen tests

It was mistakenly added to these files.

libstdc++-v3/ChangeLog:

	* testsuite/24_iterators/range_generators/01.cc: Drop GCC
	Runtime Library Exception.
	* testsuite/24_iterators/range_generators/02.cc: Drop GCC
	Runtime Library Exception.
	* testsuite/24_iterators/range_generators/copy.cc: Drop GCC
	Runtime Library Exception.
	* testsuite/24_iterators/range_generators/except.cc: Drop GCC
	Runtime Library Exception.
	* testsuite/24_iterators/range_generators/subrange.cc: Drop GCC
	Runtime Library Exception.
	* testsuite/24_iterators/range_generators/synopsis.cc: Drop GCC
	Runtime Library Exception.
	* testsuite/24_iterators/range_generators/iter_deref_return.cc:
	Drop GCC Runtime Library Exception from the "You should have
	received a copy" paragraph.