There is mkstemp() check by AC_REPLACE_FUNCS() in
configure.ac. If mkstemp() isn't found, mkstemp() is defined
by gnulib-tool.

But mkstemp() is always defined in libguile/mkstemp.c. If we
define mkstemp() by gnulib-tool, mkstemp() is defined
twice. It caused a link error.

The situation is caused when we cross-compile Guile by MinGW
because mkstemp() doesn't exist on Windows.

Here is an error message on my environment:

      CCLD     libguile-2.0.la
    ../lib/.libs/libgnu.a(mkstemp.o): In function `mkstemp':
    .../lib/mkstemp.c:48: multiple definition of `mkstemp'
    .libs/libguile_2.0_la-mkstemp.o:.../libguile/mkstemp.c:68: first defined here
    collect2: error: ld returned 1 exit status
    Makefile:2242: recipe for target 'libguile-2.0.la' failed
    make[3]: *** [libguile-2.0.la] Error 1


I attach a patch to fix this problem.