libcryptopp is broken on x86 due to using libstdc++

[barracuda156]

INFO: Crypto++ was built without LLVM libc++. If you are using the library
INFO: with modern Xcode, then you should add -stdlib=libc++ to CXXFLAGS. It is
INFO: already present in the makefile, and you only need to uncomment it.
. . .
libcryptopp is using libstdc++ (this installation is configured to use libc++)
--->  Found 1 broken port, determining rebuild order
You can always run 'port rev-upgrade' again to fix errors.
The following ports will be rebuilt: libcryptopp @8.9.0

[barracuda156]

Ah, it does not use configure also, so a standard way does not help:

if {${configure.cxx_stdlib} eq "libc++"} {
    configure.cxxflags-append \
                   -stdlib=libc++
    configure.ldflags-append \
                   -stdlib=libc++
}

This gets ignored.

[ryandesign (Ryan Carsten Schmidt)]

MacPorts already adds -stdlib=libc++ to cxxflags so this suggests the build is ignoring our cxxflags. The buildbot logs have already expired so please attach your main.log file to see if we can spot any other confirmation of that.

[barracuda156]

In 693792562d02e0ab6eec0d6b1b092a4bac4727f5/macports-ports (master):

libcryptopp: fix linking to libc++

Fixes: #69597