Bring back nocombreloc if dumping

Bring back nocombreloc if dumping

Without this patch, Emacs dumps core on Fedora 28 x86-64
when configured via "CC='gcc -m32' --enable-gcc-warnings
--without-imagemagick --without-gif --with-modules
PKG_CONFIG_LIBDIR=/usr/lib/pkgconfig:/usr/share/pkgconfig".
and then when run normally in a windowing system.
'make check' and 'emacs -nw' work OK even without the patch.
* configure.ac (LD_SWITCH_SYSTEM_TEMACS): Prepend
-znocombreloc if supported and if dumping.  This mostly
reverts 2018-06-15T21:37:39!eggert@cs.ucla.edu "Remove old
combreloc hack".