* gnu/local.mk (dist_patch_DATA): Add Smalltalk patch.
* gnu/packages/patches/smalltalk-multiplication-overflow.patch: Patch
from upstream commit 72ada189aba0283c551ead16635c1983968080b8.
* gnu/packages/smalltalk.scm (smalltalk): Use patch and link with gmp
and lightning libraries instead of the included source.
