Allow building with the 32 bit mingw-w64 toolchain.
* scripts/autogen.sh <--build-w32>: Support i686-w64-mingw32 and use it by default if installed. * keyserver/gpgkeys_ldap.c (my_ldap_start_tls_s): Define macro depending on compiler version. (main): Use new macro. * util/miscutil.c [!HAVE_TIMEGM]: Add prototype for the timegm autoconf replacement function.
It seems that the LDAP keyserver helper build with the old mingw32
toolchain never worked correctly for LDAPS. The prototype there for
ldap_start_tls_s is plainly wrong for Windows. Anyway I included
special support so not to break building with the old compiler.