cmake-bootstrap @3.9.6+universal: Bad CPU type in executable

[ryandesign (Ryan Carsten Schmidt)]

On a Snow Leopard i386 machine I'm no longer able to upgrade many ports—those that depend on xz (for example because they use an xz-compressed distfile) because xz eventually (through clang-11-bootstrap) depends on cmake-bootstrap, which automatically builds itself with the universal variant, which fails because it uses the muniversal portgroup and the x86_64 part of the build wants to run an x86_64 executable which of course will fail on an i386 machine.

main.log:

:info:configure ---------------------------------------------
:info:configure CMake 3.9.6, Copyright 2000-2017 Kitware, Inc. and Contributors
:info:configure ---------------------------------------------
:info:configure Error when bootstrapping CMake:
:info:configure Cannot find appropriate C compiler on this system.
:info:configure Please specify one using environment variable CC.
:info:configure See cmake_bootstrap.log for compilers attempted.
:info:configure ---------------------------------------------
:info:configure Log of errors: /opt/bblocal/var/macports/build/_opt_bblocal_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_devel_cmake-bootstrap/cmake-bootstrap/work/cmake-3.9.6-x86_64/Bootstrap.cmk/cmake_bootstrap.log
:info:configure ---------------------------------------------

cmake_bootstrap.log:

Try: /usr/bin/gcc-4.2
Line: /usr/bin/gcc-4.2 -pipe -Os -arch x86_64 cmake_bootstrap_78513_test.c -o cmake_bootstrap_78513_test
----------  file   -----------------------

#ifdef __cplusplus
# error "The CMAKE_C_COMPILER is set to a C++ compiler"
#endif

#include<stdio.h>

#if defined(__CLASSIC_C__)
int main(argc, argv)
  int argc;
  char* argv[];
#else
int main(int argc, char* argv[])
#endif
{
  printf("%d%c", (argv != 0), (char)0x0a);
  return argc-1;
}

------------------------------------------
/opt/bblocal/var/macports/build/_opt_bblocal_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_devel_cmake-bootstrap/cmake-bootstrap/work/cmake-3.9.6-x86_64/bootstrap: line 687: ./cmake_bootstrap_78513_test: Bad CPU type in executable
Test produced non-zero return code
Checking whether  supports -std=gnu11
Try: 
Line:  -pipe -Os -arch x86_64 -std=gnu11 cmake_bootstrap_78513_test.c -o cmake_bootstrap_78513_test
----------  file   -----------------------

#ifdef __cplusplus
# error "The CMAKE_C_COMPILER is set to a C++ compiler"
#endif

#include<stdio.h>

#if defined(__CLASSIC_C__)
int main(argc, argv)
  int argc;
  char* argv[];
#else
int main(int argc, char* argv[])
#endif
{
  printf("%d%c", (argv != 0), (char)0x0a);
  return argc-1;
}

------------------------------------------
/opt/bblocal/var/macports/build/_opt_bblocal_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_devel_cmake-bootstrap/cmake-bootstrap/work/cmake-3.9.6-x86_64/bootstrap: line 677: : command not found
Test failed to compile