base/perlnative/pythonnative/gzipnative: Add a new variable to enable easier handling of native path issues

If something is listed in ASSUME_PROVIDED but also manually built (like bzip2-native and
bzip2-replacement-native), we need to ensure that the installed binaries are only accessed
for things which list the provider in DEPENDS.

This patch adds a generic mechanism to handle this instead of everything reinventing the
wheel. EXTRANATIVEPATH += "perl-native" will ensure that ${STAGING_BINDIR_NATIVE}/perl-native
is added to PATH.

This means that:

a) Such providers should install to ${bindir}/xxx-native
b) Should PROVIDE += "xxxx-replacement-native"
c) That users should DEPEND on xxx-replacement-native and have EXTRANATIVEPATH += "xxx-native"

This patch enables this at the core level, the bzip2 recipe still needs adjusting to work
like this along with adjustment of the users of bzip2-replacement-native (python-native?).

(From OE-Core rev: 14b70cd222519e5bccaca955334787f123d9fc54)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/classes/pythonnative.bbclass

@@ -1,3 +1,3 @@
 PYTHON="${STAGING_BINDIR_NATIVE}/python-native/python"
-PATH_prepend = "${STAGING_BINDIR_NATIVE}/python-native:"
+EXTRANATIVEPATH += "python-native"
 DEPENDS += " python-native "