No-libtool Autotools shared libraries: Welcome to Portability Hell

configure.ac

AC_PREREQ([2.64])
AC_INIT([tt], [0])
AC_CONFIG_SRCDIR([tt.c])
AC_CONFIG_AUX_DIR([build-auxf])
AC_CONFIG_MACRO_DIR([build-m4])
AM_INIT_AUTOMAKE([1.11 foreign -Wall])
AC_CONFIG_HEADERS([config.h])

AC_PROG_CC

AC_CONFIG_FILES([Makefile])
AC_OUTPUT

Makefile.am

# alias libdir to prevent Automake from whining trying to be too smart
sodir = $(libdir)

so_PROGRAMS = libtt.so
bin_PROGRAMS = ttp

libtt_so_SOURCES = tt.c
libtt_so_CFLAGS = -fPIC
libtt_so_LDFLAGS = -shared

ttp_SOURCES = ttp.c
ttp_LDADD = -ltt -L$(builddir)

# FIXME: why does adding libtt.so as a dependency of "ttp$(EXEEXT)" breaks the
# build??  this is crazy.  hack around by making target "all" depend on
# libtt.so before ttp$(EXEEXT)
#ttp$(EXEEXT): libtt.so
all: libtt.so ttp$(EXEEXT)

tt.c

#include <stdio.h>

int foo (void) {
  printf("foo!\n");
  return 0;
}

ttp.c

extern int foo (void);

int main (void)
{
  return foo ();
}