shared library support for HP-UX 10

shared library support for HP-UX 10

Our somewhat outdated HP-UX support (which was targeted at HP-UX 10, not 11)
does not have support for shared library initialization and finalization
functions, nor for shared library export lists.  The former was causing
compilation failures unless shared library support was disabled.

* include/k5-platform.h: Expand on init/fini comments some more.
(MAKE_FINI_FUNCTION): Add an HP-UX specific variant that defines an auxiliary
function fitting the signature of HP-UX 10 library combined
initializer/finalizer functions.

* config/lib.in (hpux10.exports): New target, constructed similar to
osf1.exports but with HP-UX 10.x linker options, no initializers, and "errno"
explicitly added to the export list.
* shlib.conf (*-*-hpux*): Combine PICFLAGS setting with SHLIB_EXPFLAGS and
LDCOMBINE setting.  Add linker option "-c hpux10.exports" to LDCOMBINE.  Set
SHLIB_EXPORT_FILE_DEP to hpux10.exports.  Set use_linker_fini_option.

ticket: new

git-svn-id: svn://anonsvn.mit.edu/krb5/trunk@17153 dc483132-0cff-0310-8789-dd5450dbe970