Various standards place dynamic libraries by default in /usr/local/lib. This includes the coding standards for the entire GNU project; see info -> Standards -> Managing Releases -> Makefile Conventions -> Directory Variables. However, /etc/ld.so.conf doesn't include /usr/local/lib, causing many surprises when trying to download and install from sources. None of this is necessary; you should be able to download & install programs "automagically" without having to set prefixes, etc. This is quite nonstandard, for example, Solaris always includes /usr/local/lib in its directory list. If "ldconfig" is the wrong package to blame, sorry; please forward it to whoever is the "right" person. In short: please add a "/usr/local/lib" entry to /etc/ld.so.conf.
While adding /usr/local/lib is the Right Thing To do in the circumstances you describe, Red Hat tries to leave /usr/local *entirely* to the local system administrator, including configuring /usr/local in /etc/ld.so.conf. The real issue is what should the default configuration be. Since Red Hat can't possibly guess where /usr/local should be inserted, we do nothing.
*** Bug 10019 has been marked as a duplicate of this bug. ***
*** Bug 182486 has been marked as a duplicate of this bug. ***