Description of problem:

js.spec has a error in which there are $ in place of % in the part which
generates the libjs.pc file. Still occurs in js-devel-1.5-5.fc5.

How reproducible:

Always

Steps to Reproduce:
1. Install js-devel
2. Run pkg-config --list-all
3. See error message (variable _prefix undefined)
4. cat /usr/lib/pkgconfig/libjs.pc
5. See the ${_prefix}, ${_libdir} and ${_includedir} in file.
  
Actual results:
${_prefix}, ${_libdir} and ${_includedir} in /usr/lib/pkgconfig/libjs.pc

Expected results:
/usr, /usr/lib and /usr/include should be in /usr/lib/pkgconfig/libjs.pc

Additional info:

Attached a patch to js.spec to fix the issue.