sgml-common-native: Convert to new style staging, remove do_stage()

sgml-common-native: Convert to new style staging, remove do_stage()

* Converted do_stage to do_install
* Replaced ${STAGING_BINDIR_NATIVE} with ${D}${bindir}, ${sysconfdir} with ${D}${sysconfdir}, ${STAGING_DATADIR} with ${D}${datadir}.
* Updated install-catalog script. it had hard coded reference to ${sysconfdir}. Changed it to ${D}${sysconfdir}.
* Used SYSROOT_PREPROCESS_FUNCS to add a function sgml_common_native_mangle.
* Write new function sgml_common_native_mangle function.
* Reverted back ${sysconfdir} path in install-catalog in sgml_common_native_mangle
* Updated path in sgml_common_native_mangle function from ${D}${datadir}/sgml/sgml-iso-entities-8879.1986/catalog to ${datadir}/sgml/sgml-iso-entities-8879.1986/catalog in sgml-ent.cat file.
* Updated path in sgml_common_native_mangle function from ${D}${sysconfdir}/sgml/sgml-ent.cat|${sysconfdir}/sgml/sgml-ent.cat to ${sysconfdir}/sgml/sgml-ent.cat in sgml-ent.cat file
* Removed ${D} path in sgml_common_native_mangle function from catalog file created by install-catalog script.
* Bump PR to "r1"

Signed-off-by: Noor Ahsan <noor_ahsan@mentor.com>