Link failure on systems lacking mkstemp

[Eli Zaretskii]

Guile 2.0.11 has mkstemp.c in lib/, from Gnulib, and it also has its
own private version in libguile/.  This causes link failures on
systems, such as MinGW, that lack mkstemp in their system libraries:

       CCLD     libguile-2.0.la
     ../lib/.libs/libgnu.a(mkstemp.o): In function `mkstemp':
     d:\gnu\guile-2.0.11\lib/mkstemp.c:48: multiple definition of `mkstemp'
     .libs/libguile_2.0_la-mkstemp.o:d:\gnu\guile-2.0.11\libguile/mkstemp.c:68: 
first defined here
     collect2.exe: error: ld returned 1 exit status
     Makefile:2242: recipe for target `libguile-2.0.la' failed
     make[3]: *** [libguile-2.0.la] Error 1
     make[3]: Leaving directory `/d/gnu/guile-2.0.11/libguile'
     Makefile:2162: recipe for target `all' failed

I think the solution is simply remove mkstemp.c from libguile/, and
all its traces from the configury that causes its dependency to be
added to libguile/Makefile.  Not sure how to do the latter, though.