autoconf-2.61's AC_LINK_IFELSE with MinGW cross-compilers

[Chris Johns]

Hello,

The autoconf-2.61 release added a 'test -x' to AC_LINK_IFELSE and that has 
broken MinGW based cross-compilers using autoconf packages in MSYS.

The change is:

http://cvs.savannah.gnu.org/viewcvs/autoconf/lib/autoconf/general.m4?root=autoconf&r1=1.931&r2=1.932

RTEMS uses AC_LINK_IFELSE and MinGW cross-compilers fail this test.

A MinGW compiler cannot set an execute bit on an executable as Windows 
provides no support for it. MSYS emulates the execute bit by pattern matching 
the file extension (.exe, .bat, .com) so a native Windows compiler creating a 
a.exe file works. Here AC_PROG_CC sets $ac_exeext to '.exe' and AC_LINK_IFELSE 
creates a .exe file. A MinGW cross-compiler such as one for RTEMS by default 
creates 'a.out' so $ac_exeext is ''.

Is the 'test -x' suitable for MSYS and a cross-compiler ?

Regards
Chris