Detect Boost.Timer with linker flags of Boost.Chrono
Detect Boost.Timer with linker flags of Boost.Chrono

Otherwise, it got an error at configure time:
> configure:19635: g++ -o conftest -fsanitize=undefined  -I/home/abe/isvar/Flint.posix/posix/opt/boost_1_64_0/include -Wl,-rpath -Wl,/home/abe/isvar/Flint.posix/posix/opt/libsbml-5.15.0/lib -Wl,-rpath -Wl,/home/abe/isvar/Flint.posix/posix/opt/sundials-2.7.0/lib -Wl,-rpath -Wl,/home/abe/isvar/Flint.posix/posix/opt/wxWidgets-3.1.0/lib -L/home/abe/isvar/Flint.posix/posix/opt/boost_1_64_0/lib conftest.o -lboost_timer-mt  >&5
> /usr/bin/ld: warning: libboost_chrono-mt.so.1.64.0, needed by /home/abe/isvar/Flint.posix/posix/opt/boost_1_64_0/lib/libboost_timer-mt.so, not found (try using -rpath or -rpath-link)
> /usr/bin/ld: warning: libboost_system-mt.so.1.64.0, needed by /home/abe/isvar/Flint.posix/posix/opt/boost_1_64_0/lib/libboost_timer-mt.so, not found (try using -rpath or -rpath-link)
> /home/abe/isvar/Flint.posix/posix/opt/boost_1_64_0/lib/libboost_timer-mt.so: undefined reference to `boost::chrono::steady_clock::now()'
> collect2: error: ld returned 1 exit status
> configure:19644: $? = 1

flintproject/Flint,flintproject/Flint