allarch.bbclass: Exclude package_do_shlibs from do_package signature

shlibs is largely useless for allarch, the particular usecase where it
fails is when DISTRO_FEATURE is changing due to libc being different e.g.

Variable package_do_shlibs value changed:
-DISTRO_FEATURES{ldconfig} = Set
+DISTRO_FEATURES{ldconfig} = Unset

musl -> glibc or other way around 'ldconfig' gets added or deleted to
DISTRO_FEATURE set, neither this distro feature nor the shlibs processing
during packaging is of interest to allarch packages which are largely
arch independent scripts

(From OE-Core rev: 06602d56d1d311562144eafe459fcea36931a34c)

Signed-off-by: Khem Raj <raj.khem@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/classes/allarch.bbclass

@@ -45,6 +45,7 @@ python () {
         # These multilib values shouldn't change allarch packages so exclude them
         d.appendVarFlag("emit_pkgdata", "vardepsexclude", " MULTILIB_VARIANTS")
         d.appendVarFlag("write_specfile", "vardepsexclude", " MULTILIBS")
+        d.appendVarFlag("do_package", "vardepsexclude", " package_do_shlibs")
     elif bb.data.inherits_class('packagegroup', d) and not bb.data.inherits_class('nativesdk', d):
         bb.error("Please ensure recipe %s sets PACKAGE_ARCH before inherit packagegroup" % d.getVar("FILE"))
 }