especially:
"I had to put CLISP under GPL because libreadline.a was something I wanted to use and I didn't want to write myself. libgmp.a is similar in this respect, and it may therefore help putting some new packages under GPL.
Building libgmp.a was just too hard work. Other people shouldn't get it for free."
this reminds me of this email conversation: http://clisp.cvs.sourceforge.net/*checkout*/clisp/clisp/doc/...
especially: "I had to put CLISP under GPL because libreadline.a was something I wanted to use and I didn't want to write myself. libgmp.a is similar in this respect, and it may therefore help putting some new packages under GPL.
Building libgmp.a was just too hard work. Other people shouldn't get it for free."