suddenly, "-arch i386" is added and all fails: e.g. libsdl

[ah]

Hi,
this is on OSX 13.6 (High Sierra) on a macbookpro/2012 (which is an 
intell 64bit i believe), and XCode 10.1 (build 10861) the last few hours 
I am experiencing a new kind of failure using macports. A couple of 
weeks ago I have installed successfully opencv. And none of the problems 
I describe here arose.

So,

Initially I wanted to do: port -s -v install dosbox

One of its dependencies, "libsdl", failed with lots of symbols undefined 
(at linking). One of the messages was "ld: warning: ignoring file 
/Library/Frameworks/AudioUnit.framework/AudioUnit.tbd, missing required 
architecture i386 in file 
/Library/Frameworks/AudioUnit.framework/AudioUnit.tbd" then "Undefined 
symbols for architecture i386: ...[lots of symbols]"

and the linking command had this in it:

   -arch i386

I have traced this to the "configure" file in libsdl's build dir (where 
macports extracted sources and attempted to build), in the following line:

/usr/bin/uname -p = `(/usr/bin/uname -p) 2>/dev/null || echo unknown`

when I replaced the righ-hand expression with just the string
x86_64

all compiled well.

Prior to this, python 3.7 also had similar problems. And I managed to 
solve them using the same method with additionally replacing all 
occurences of "arch -i386" and "extract i386" from configure script also 
(this is from my memory).

I have explicitly set :
export LDFLAGS=
export CFLAGS=
export CXXFLAGS=
before :
port -v -s libsdl

btw,
/bin/uname -p reports i386
and so is
/opt/local/libexec/gnubin/uname -p

whereas
/bin/uname -m reports x86_64

Lately, I did install autotools port, perhaps that broke things somehow, 
not being aware about the osx idiotic "uname -p" reporting i386? *(btw 
my kernel I believe is 64bit, "About this mac->System 
report->Software->Extensions->64-0Bit (Intel): YES"

also :

uname -a
reports  x86_64