Limit the libraries pulled in when dynamic linking.

See also https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=745543

tools/heimdal-gssapi.pc.in

@@ -8,6 +8,7 @@ Name: @PACKAGE@
 Description: Heimdal is an implementation of Kerberos 5, freely available under a three clause BSD style license.
 Version: @VERSION@
 URL: http://www.pdc.kth.se/heimdal/
-Requires: heimdal-krb5
-Libs: -L${libdir} -lgssapi -lheimntlm @LIB_crypt@
+Requires.private: heimdal-krb5
+Libs: -L${libdir} -lgssapi
+Libs.private: -lheimntlm @LIB_crypt@
 Cflags: -I${includedir}