Remove alleged support for last-millennium Unixes

Remove workarounds for NeXTStep (last released in 1995), SunOS (1994),
HP-UX 9.x (1992) and 10.x (1995), OSF/1 / Digital UNIX / Tru64 UNIX
4.x (1999), and AIX 4.x (1999).

HP-UX 11 implements dlopen(), so dropping support for earlier versions
also lets us remove the HP-UX-specific gmodule-dld.

https://bugzilla.gnome.org/show_bug.cgi?id=710519

gmodule/Makefile.am

@@ -13,7 +13,6 @@ EXTRA_DIST +=				\
 		makefile.msc.in 	\
 		gmoduleconf.h.in 	\
 		gmodule-dl.c		\
-		gmodule-dld.c		\
 		gmodule-dyld.c		\
 		gmodule-win32.c		\
 		gmodule-ar.c		\