Disable FAM support in RHEL

FAM support in GLib requires Gamin component, which has various issues
and is unmaintained for years. GLib is the only component that requires
it in RHEL. So let's do not build the optional glib2-fam subpackage on
RHEL so Gamin can be dropped out from there. I am not doing the same
change for Fedora as there are more components that require Gamin. So
the subpackage can be held there yet for some time. The only reason why
this change hasn't been done earlier is the fact that FAM support was
needed for DConf functionality when the home directory is on NFS. But
this shouldn't be a problem nowadays thanks to the following commit:
https://gitlab.gnome.org/GNOME/glib/-/commit/7427bb71.

glib2.spec

@@ -69,6 +69,7 @@ BuildArch: noarch
 %description doc
 The glib2-doc package includes documentation for the GLib library.
 
+%if 0%{?fedora} || 0%{?rhel} <= 8
 %package fam
 Summary: FAM monitoring module for GIO
 Requires: %{name}%{?_isa} = %{version}-%{release}
@@ -76,6 +77,7 @@ BuildRequires: gamin-devel
 
 %description fam
 The glib2-fam package contains the FAM (File Alteration Monitor) module for GIO.
+%endif
 
 %if 0%{?fedora}
 %package static
@@ -109,7 +111,9 @@ rm glib/pcre/*.[ch]
     -Ddtrace=true \
     -Dsystemtap=true \
     -Dgtk_doc=true \
+%if 0%{?fedora} || 0%{?rhel} <= 8
     -Dfam=true \
+%endif
     -Dinstalled_tests=true \
 %if 0%{?rhel}
     -Dgnutls=true \
@@ -225,8 +229,10 @@ glib-compile-schemas %{_datadir}/glib-2.0/schemas &> /dev/null || :
 %files doc
 %doc %{_datadir}/gtk-doc/html/*
 
+%if 0%{?fedora} || 0%{?rhel} <= 8
 %files fam
 %{_libdir}/gio/modules/libgiofam.so
+%endif
 
 %if 0%{?fedora}
 %files static