Fix tests/Makefile.am
Fix tests/Makefile.am

Add -lpthread for the multi-thread program. This is needed at list of
Fedora 22, and apparently on some other OSs.
Add the existing mem-leak program.
Add LDFLAGS.

MadBomber/link-grammar,opencog/link-grammar,ampli/link-grammar,opencog/link-grammar,opencog/link-grammar,MadBomber/link-grammar,linas/link-grammar,linas/link-grammar,linas/link-grammar,ampli/link-grammar,MadBomber/link-grammar,MadBomber/link-grammar,ampli/link-grammar,MadBomber/link-grammar,MadBomber/link-grammar,opencog/link-grammar,linas/link-grammar,ampli/link-grammar,ampli/link-grammar,ampli/link-grammar,MadBomber/link-grammar,linas/link-grammar,linas/link-grammar,opencog/link-grammar,ampli/link-grammar,MadBomber/link-grammar,linas/link-grammar,opencog/link-grammar,linas/link-grammar,opencog/link-grammar,ampli/link-grammar,opencog/link-grammar,ampli/link-grammar,linas/link-grammar,opencog/link-grammar