Comment 2 for bug 1490585

This does not seem to be an architecture related issue. See the following further analysis:

rpg@rpgoldman-2: ~/lisp/asdf/test $ gcc -o /Users/rpg/lisp/asdf/build/fasls/ecl-16.0.0-unknown-macosx-x64/asdf/test/ecl-make-image/test.fas -L /usr/local/stow/ecl/lib/ /private/var/folders/xq/ll1d80qs7hnbw3253yc1_x6m0000gn/T/eclinitwwC3Rd.o /Users/rpg/lisp/asdf/build/fasls/ecl-16.0.0-unknown-macosx-x64/asdf/test/ecl-make-image/hello.o -bundle -lecl -lpthread -lm -v
Apple LLVM version 7.3.0 (clang-703.0.29)
Target: x86_64-apple-darwin15.5.0
Thread model: posix
InstalledDir: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin
 "/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/ld" -demangle -dynamic -arch x86_64 -bundle -macosx_version_min 10.11.0 -o /Users/rpg/lisp/asdf/build/fasls/ecl-16.0.0-unknown-macosx-x64/asdf/test/ecl-make-image/test.fas -L/usr/local/stow/ecl/lib/ /private/var/folders/xq/ll1d80qs7hnbw3253yc1_x6m0000gn/T/eclinitwwC3Rd.o /Users/rpg/lisp/asdf/build/fasls/ecl-16.0.0-unknown-macosx-x64/asdf/test/ecl-make-image/hello.o -lecl -lpthread -lm -lSystem /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../lib/clang/7.3.0/lib/darwin/libclang_rt.osx.a
Undefined symbols for architecture x86_64:
  "_hello_string", referenced from:
      __eclKh01T9WuI9OGL_rPv3Zi21 in hello.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
rpg@rpgoldman-2: ~/lisp/asdf/test $ nm /Users/rpg/lisp/asdf/build/fasls/ecl-16.0.0-unknown-macosx-x64/asdf/test/ecl-make-image/hello.o
00000000000058b8 b _Cblock
0000000000000190 t _LC1__g0
0000000000000330 s _LC1__g0._ecl_descriptors
00000000000058c0 b _VV
                 U ___stack_chk_fail
                 U ___stack_chk_guard
0000000000000000 T __eclKh01T9WuI9OGL_rPv3Zi21
                 U _cl_symbols
00000000000002f0 s _compiler_data_text
0000000000000300 s _compiler_data_text1
                 U _ecl_cs_overflow
                 U _ecl_function_dispatch
                 U _ecl_make_cfun
                 U _ecl_make_foreign_data
                 U _ecl_make_simple_base_string
                 U _ecl_print
                 U _ecl_process_env
                 U _hello_string
                 U _si_get_sysprop
                 U _si_put_sysprop
                 U _si_select_package
rpg@rpgoldman-2: ~/lisp/asdf/test $ file
Usage: file [-bchikLNnprsvz0] [-e test] [-f namefile] [-F separator] [-m magicfiles] [-M magicfiles] file...
       file -C -m magicfiles
Try `file --help' for more information.
rpg@rpgoldman-2: ~/lisp/asdf/test $ file /Users/rpg/lisp/asdf/build/fasls/ecl-16.0.0-unknown-macosx-x64/asdf/test/ecl-make-image/hello.o
/Users/rpg/lisp/asdf/build/fasls/ecl-16.0.0-unknown-macosx-x64/asdf/test/ecl-make-image/hello.o: Mach-O 64-bit object x86_64
rpg@rpgoldman-2: ~/lisp/asdf/test $ file /private/var/folders/xq/ll1d80qs7hnbw3253yc1_x6m0000gn/T/eclinitwwC3Rd.o
/private/var/folders/xq/ll1d80qs7hnbw3253yc1_x6m0000gn/T/eclinitwwC3Rd.o: Mach-O 64-bit object x86_64
rpg@rpgoldman-2: ~/lisp/asdf/test $ nm /private/var/folders/xq/ll1d80qs7hnbw3253yc1_x6m0000gn/T/eclinitwwC3Rd.o
                 U __eclKh01T9WuI9OGL_rPv3Zi21
                 U _ecl_init_module
                 U _ecl_make_codeblock
0000000000000000 T _init_fas_CODE
0000000000004888 b _init_fas_CODE.Cblock