[ping][PATCH] configure.ac: Also quote '$' in tbaseargs

[Maciej W. Rozycki]

Hi,

 Would anyone please have a look at:

http://gcc.gnu.org/ml/gcc-patches/2012-05/msg00044.html

I know this is trivial boring stuff, but perhaps especially because of 
this let's get rid of it ASAP?  Thanks.

  Maciej