jbigkit: adding the library spec for dependents (#24103)

var/spack/repos/builtin/packages/jbigkit/package.py

@@ -33,3 +33,9 @@ def install(self, spec, prefix):
             mkdir(prefix.bin)
             for f in ['tstcodec', 'tstcodec85']:
                 install(f, prefix.bin)
+
+    @property
+    def libs(self):
+        return find_libraries(
+            "libjbig*", root=self.prefix, shared=False, recursive=True
+        )