libidn2 fails to build due to nm

[rmottola (Riccardo)]

Libidn2 fails to build on Leopard - 10.5

al/lib ../gl/libgnu.la  -lunistring 
libtool: link: /usr/bin/nm -p  .libs/idna.o .libs/lookup.o .libs/decode.o .libs/register.o .libs/bidi.o .libs/version.o .libs/error.o .libs/puny_encode.o .libs/puny_decode.o .libs/free.o .libs/data.o .libs/tr46map.o .libs/tables.o .libs/context.o   ../gl/.libs/libgnu.a |  | /usr/bin/sed 's/.* //' | sort | uniq > .libs/libidn2.exp
../libtool: eval: line 1720: syntax error near unexpected token `|'
../libtool: eval: line 1720: `/usr/bin/nm -p  .libs/idna.o .libs/lookup.o .libs/decode.o .libs/register.o .libs/bidi.o .libs/version.o .libs/error.o .libs/puny_encode.o .libs/puny_decode.o .libs/free.o .libs/data.o .libs/tr46map.o .libs/tables.o .libs/context.o   ../gl/.libs/libgnu.a |  | /usr/bin/sed 's/.* //' | sort | uniq > .libs/libidn2.exp'
make[3]: *** [libidn2.la] Error 1

this is due to old nm being used. I applied a fix proposed by @kencu in another port and it works:

if {${os.platform} eq "darwin" && ${os.major} < 10} {
    depends_build-append port:cctools
    configure.env-append NM=${prefix}/bin/nm
    configure.args-append lt_cv_path_NM=${prefix}/bin/nm
}

[Schamschula (Marius Schamschula)]

In 8cd9daac5319c3ce964411698a8e6c9dbab04be6/macports-ports (master):

libidn2: fix nm issue on Leopard

Closes: #60204