...not 16-bit unsigned.  Word2007RTFSpec9.docx states "A small number of control
words take values in the range −2,147,483,648 to 2,147,483,647 (32-bit signed
integer)." and for \picwN, \pichN, \picwgoalN, and \pichgoalN it states "The N
argument is a long integer."

This was found with Clang's new -fsanitize=implicit-conversion during
CppunitTest_writerfilter_rtftok, where
writerfilter/qa/cppunittests/rtftok/data/pass/TCI-TN65GP-DDRHDLL-partial.rtf
contains "\pich81306":

> Testing file:///home/sbergman/lo/core/writerfilter/qa/cppunittests/rtftok/data/pass/TCI-TN65GP-DDRHDLL-partial.rtf:
[...]
> writerfilter/source/rtftok/rtfdispatchvalue.cxx:770:48: runtime error: implicit conversion from type 'int' of value 81306 (32-bit, signed) to type 'sal_uInt16' (aka 'unsigned short') changed the value to 15770 (16-bit, unsigned)
>  #0 in writerfilter::rtftok::RTFDocumentImpl::dispatchValue(writerfilter::rtftok::RTFKeyword, int) at writerfilter/source/rtftok/rtfdispatchvalue.cxx:770:48 (instdir/program/libwriterfilterlo.so +0xb96f2f)
>  #1 in writerfilter::rtftok::RTFTokenizer::dispatchKeyword(rtl::OString const&, bool, int) at writerfilter/source/rtftok/rtftokenizer.cxx:311:29 (instdir/program/libwriterfilterlo.so +0xd86c93)
>  #2 in writerfilter::rtftok::RTFTokenizer::resolveKeyword() at writerfilter/source/rtftok/rtftokenizer.cxx:243:12 (instdir/program/libwriterfilterlo.so +0xd84b06)
>  #3 in writerfilter::rtftok::RTFTokenizer::resolveParse() at writerfilter/source/rtftok/rtftokenizer.cxx:123:27 (instdir/program/libwriterfilterlo.so +0xd8299a)
>  #4 in writerfilter::rtftok::RTFDocumentImpl::resolve(writerfilter::Stream&) at writerfilter/source/rtftok/rtfdocumentimpl.cxx:786:27 (instdir/program/libwriterfilterlo.so +0xbf03bd)
>  #5 in RtfFilter::filter(com::sun::star::uno::Sequence<com::sun::star::beans::PropertyValue> const&) at writerfilter/source/filter/RtfFilter.cxx:144:20 (instdir/program/libwriterfilterlo.so +0x132d911)
>  #6 in RtfTest::load(rtl::OUString const&, rtl::OUString const&, rtl::OUString const&, SfxFilterFlags, SotClipboardFormatId, unsigned int) at writerfilter/qa/cppunittests/rtftok/testrtftok.cxx:58:27 (workdir/LinkTarget/CppunitTest/libtest_writerfilter_rtftok.so +0x15c6e)
>  #7 in test::FiltersTest::recursiveScan(test::filterStatus, rtl::OUString const&, rtl::OUString const&, rtl::OUString const&, SfxFilterFlags, SotClipboardFormatId, unsigned int, bool) at unotest/source/cpp/filters-test.cxx:130:20 (workdir/LinkTarget/CppunitTest/../Library/libunotest.so +0x5724c)
>  #8 in test::FiltersTest::testDir(rtl::OUString const&, rtl::OUString const&, rtl::OUString const&, SfxFilterFlags, SotClipboardFormatId, unsigned int, bool) at unotest/source/cpp/filters-test.cxx:155:5 (workdir/LinkTarget/CppunitTest/../Library/libunotest.so +0x57ec9)
>  #9 in RtfTest::test() at writerfilter/qa/cppunittests/rtftok/testrtftok.cxx:78:5 (workdir/LinkTarget/CppunitTest/libtest_writerfilter_rtftok.so +0x16214)

(Needs to add o3tl::clamp as a compatibility wrapper for C++17 std::clamp.)

Change-Id: I515e70a435c2585777062fd5a27d1de8ddbe1b74
Reviewed-on: https://gerrit.libreoffice.org/59038Reviewed-by: Miklos Vajna <vmiklos@collabora.co.uk>
Tested-by: Jenkins