Gah, I hate gcc. AC_TRY_COMPILE() produces code of the form

Gah, I hate gcc.  AC_TRY_COMPILE() produces code of the form
'int main() { ... }'.  When -Werror -Wstrict-prototypes is given to gcc, it
thinks the above code snippet is an error, and aborts.  This was making
DPKG_C_GCC_TRY_WARNS disable some -W options.  So, I no longer use
AC_TRY_COMPILE.