symengine @0.9.0: Undefined symbols: "_futimens"

[ryandesign (Ryan Carsten Schmidt)]

symengine fails to build on Yosemite, El Capitan, and Sierra:

​https://build.macports.org/builders/ports-10.12_x86_64-builder/builds/232424/steps/install-port/logs/stdio

Undefined symbols for architecture x86_64:
  "_futimens", referenced from:
      llvm::sys::fs::setLastAccessAndModificationTime(int, std::__1::chrono::time_point<std::__1::chrono::system_clock, std::__1::chrono::duration<long long, std::__1::ratio<1l, 1000000000l> > >, std::__1::chrono::time_point<std::__1::chrono::system_clock, std::__1::chrono::duration<long long, std::__1::ratio<1l, 1000000000l> > >) in libLLVMSupport.a(Path.cpp.o)

legacysupport, which symengine already includes, provides futimens, but the port specifies that legacysupport is only needed on Darwin 13 and earlier:

​https://github.com/macports/macports-ports/blob/f79cf03e01e88ec9673426f63369d3d98c5c5ac6/math/symengine/Portfile#L87

Evidently it's needed on Darwin 16 and earlier.

[barracuda156]

Is this still an issue?

[ryandesign (Ryan Carsten Schmidt)]

In 26910dda289381ee1b0ee1394e1495a45d90be4b/macports-ports (master):

symengine: Use legacysupport for futimens

Closes: #67510