[MacPorts] #58032: clang-7.0 currently on the buildbot is broken on 10.7

[MacPorts]

#58032: clang-7.0 currently on the buildbot is broken on 10.7
--------------------+-----------------------
 Reporter:  kencu   |      Owner:  kencu
     Type:  defect  |     Status:  assigned
 Priority:  Normal  |  Milestone:
Component:  ports   |    Version:
 Keywords:          |       Port:  clang-7.0
--------------------+-----------------------
 {{{
 $ /opt/local/bin/clang++-mp-7.0
 Stack dump:
 0.      Program arguments: /opt/local/libexec/llvm-7.0/bin/clang++
 0  libLLVM.dylib     0x000000010b2ead49
 llvm::sys::PrintStackTrace(llvm::raw_ostream&) + 40
 1  libLLVM.dylib     0x000000010b2ea691 llvm::sys::RunSignalHandlers() +
 51
 2  libLLVM.dylib     0x000000010b2eb19c SignalHandler(int) + 119
 3  libsystem_c.dylib 0x00007fff8e3cbcfa _sigtramp + 26
 4  libsystem_c.dylib 0x0000003900000012 _sigtramp + 1908622130
 5  clang++           0x0000000109c5fda0
 llvm::iterator_range<llvm::opt::arg_iterator<llvm::opt::Arg* const*,
 sizeof...(clang::driver::options::ID, clang::driver::options::ID)> >
 llvm::opt::ArgList::filtered<clang::driver::options::ID,
 clang::driver::options::ID>(clang::driver::options::ID,
 clang::driver::options::ID) const + 68
 6  clang++           0x0000000109c5d728 llvm::opt::Arg*
 llvm::opt::ArgList::getLastArg<clang::driver::options::ID,
 clang::driver::options::ID>(clang::driver::options::ID,
 clang::driver::options::ID) const + 36
 7  clang++           0x0000000109c43dfc
 clang::ParseDiagnosticArgs(clang::DiagnosticOptions&, llvm::opt::ArgList&,
 clang::DiagnosticsEngine*, bool, bool) + 202
 8  clang++           0x00000001098ce158 main + 5261
 9  clang++           0x00000001098ccb48 start + 52
 10 clang++           0x0000000000000001 start + 4134745325
 Segmentation fault: 11
 }}}

 most likely we need to rebuild `llvm-7.0` with a different `clang`
 compiler that the one that is currently building it.

-- 
Ticket URL: <https://trac.macports.org/ticket/58032>
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